The change which made copy_xstate_to_uabi_buf() usable for
[x]fpregs_get() removed the zeroing of the header which means the
header, which is copied to user space later, contains except for the
xfeatures member, random stack content.
Add the memset() back to zero it before usage.
Fixes: eb6f51723f ("x86/fpu: Make copy_xstate_to_kernel() usable for [x]fpregs_get()")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/875yy3wb8h.ffs@nanos.tec.linutronix.de
There is no reason to do an extra XRSTOR from init_fpstate for feature
bits which have been cleared by user space in the FX magic xfeatures
storage.
Just clear them in the task's XSTATE header and do a full restore which
will put these cleared features into init state.
There is no real difference in performance because the current code
already does a full restore when the xfeatures bits are preserved as the
signal frame setup has stored them, which is the full UABI feature set.
[ bp: Use the negated mxcsr_feature_mask in the MXCSR check. ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121457.804115017@linutronix.de
If *RSTOR raises an exception, then the slow path is taken. That's wrong
because if the reason was not #PF then going through the slow path is waste
of time because that will end up with the same conclusion that the data is
invalid.
Now that the wrapper around *RSTOR return an negative error code, which is
the negated trap number, it's possible to differentiate.
If the *RSTOR raised #PF then handle it directly in the fast path and if it
was some other exception, e.g. #GP, then give up and do not try the fast
path.
This removes the legacy frame FRSTOR code from the slow path because FRSTOR
is not a ia32_fxstate frame and is therefore handled in the fast path.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121457.696022863@linutronix.de
Now that user_xfeatures is correctly set when xsave is enabled, remove
the duplicated initialization of components.
Rename the function while at it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121457.377341297@linutronix.de
Utilize the check for the extended state magic in the FX software reserved
bytes and set the parameters for restoring fx_only in the relevant members
of fw_sw_user.
This allows further cleanups on top because the data is consistent.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121457.277738268@linutronix.de
Checking for the XSTATE buffer being 64-byte aligned, and if not,
deciding just to restore the FXSR state is daft.
If user space provides an unaligned math frame and has the extended state
magic set in the FX software reserved bytes, then it really can keep the
pieces.
If the frame is unaligned and the FX software magic is not set, then
fx_only is already set and the restore will use fxrstor.
Remove it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121457.184149902@linutronix.de
__fpu__restore_sig() is convoluted and some of the basic checks can
trivially be done in the calling function as well as the final error
handling of clearing user state.
[ bp: Fixup typos. ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121457.086336154@linutronix.de
PKRU for a task is stored in task->thread.pkru when the task is scheduled
out. For 'current' the authoritative source of PKRU is the hardware.
fpu_reset_fpstate() has two callers:
1) fpu__clear_user_states() for !FPU systems. For those PKRU is irrelevant
2) fpu_flush_thread() which is invoked from flush_thread(). flush_thread()
resets the hardware to the kernel restrictive default value.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121456.802850233@linutronix.de
As the PKRU state is managed separately restoring it from the xstate
buffer would be counterproductive as it might either restore a stale
value or reinit the PKRU state to 0.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121456.606745195@linutronix.de
One nice thing about having PKRU be XSAVE-managed is that it gets naturally
exposed into the XSAVE-using ABIs. Now that XSAVE will not be used to
manage PKRU, these ABIs need to be manually enabled to deal with PKRU.
ptrace() uses copy_uabi_xstate_to_kernel() to collect the tracee's
XSTATE. As PKRU is not in the task's XSTATE buffer, use task->thread.pkru
for filling in up the ptrace buffer.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121456.508770763@linutronix.de
switch_to() and flush_thread() write the task's PKRU value eagerly so
the PKRU value of current is always valid in the hardware.
That means there is no point in restoring PKRU on exit to user or when
reactivating the task's FPU registers in the signal frame setup path.
This allows to remove all the xstate buffer updates with PKRU values once
the PKRU state is stored in thread struct while a task is scheduled out.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121456.303919033@linutronix.de
Rename it so it's clear that this is about user ABI features which can
differ from the feature set which the kernel saves and restores because the
kernel handles e.g. PKRU differently. But the user ABI (ptrace, signal
frame) expects it to be there.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121456.211585137@linutronix.de
copy_kernel_to_fpregs() restores all xfeatures but it is also the place
where the AMD FXSAVE_LEAK bug is handled.
That prevents fpregs_restore_userregs() to limit the restored features,
which is required to untangle PKRU and XSTATE handling and also for the
upcoming supervisor state management.
Move the FXSAVE_LEAK quirk into __copy_kernel_to_fpregs() and deinline that
function which has become rather fat.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121456.114271278@linutronix.de
Rename it so that it becomes entirely clear what this function is
about. It's purpose is to restore the FPU registers to the state which was
saved in the task's FPU memory state either at context switch or by an in
kernel FPU user.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121456.018867925@linutronix.de
fpu__clear() currently resets both register state and kernel XSAVE buffer
state. It has two modes: one for all state (supervisor and user) and
another for user state only. fpu__clear_all() uses the "all state"
(user_only=0) mode, while a number of signal paths use the user_only=1
mode.
Make fpu__clear() work only for user state (user_only=1) and remove the
"all state" (user_only=0) code. Rename it to match so it can be used by
the signal paths.
Replace the "all state" (user_only=0) fpu__clear() functionality. Use the
TIF_NEED_FPU_LOAD functionality instead of making any actual hardware
registers changes in this path.
Instead of invoking fpu__initialize() just memcpy() init_fpstate into the
task's FPU state because that has already the correct format and in case of
PKRU also contains the default PKRU value. Move the actual PKRU write out
into flush_thread() where it belongs and where it will end up anyway when
PKRU and XSTATE have been untangled.
For bisectability a workaround is required which stores the PKRU value in
the xstate memory until PKRU is untangled from XSTATE for context
switching and return to user.
[ Dave Hansen: Polished changelog ]
[ tglx: Fixed the PKRU fallout ]
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121455.922729522@linutronix.de
There is no point in using copy_init_pkru_to_fpregs() which in turn calls
write_pkru(). write_pkru() tries to fiddle with the task's xstate buffer
for nothing because the XRSTOR[S](init_fpstate) just cleared the xfeature
flag in the xstate header which makes get_xsave_addr() fail.
It's a useless exercise anyway because the reinitialization activates the
FPU so before the task's xstate buffer can be used again a XRSTOR[S] must
happen which in turn dumps the PKRU value.
Get rid of the now unused copy_init_pkru_to_fpregs().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121455.732508792@linutronix.de
X86_FEATURE_OSPKE is enabled first on the boot CPU and the feature flag is
set. Secondary CPUs have to enable CR4.PKE as well and set their per CPU
feature flag. That's ineffective because all call sites have checks for
boot_cpu_data.
Make it smarter and force the feature flag when PKU is enabled on the boot
cpu which allows then to use cpu_feature_enabled(X86_FEATURE_OSPKE) all
over the place. That either compiles the code out when PKEY support is
disabled in Kconfig or uses a static_cpu_has() for the feature check which
makes a significant difference in hotpaths, e.g. context switch.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121455.305113644@linutronix.de
Both function names are a misnomer.
fpu__save() is actually about synchronizing the hardware register state
into the task's memory state so that either coredump or a math exception
handler can inspect the state at the time where the problem happens.
The function guarantees to preserve the register state, while "save" is a
common terminology for saving the current state so it can be modified and
restored later. This is clearly not the case here.
Rename it to fpu_sync_fpstate().
fpu__copy() is used to clone the current task's FPU state when duplicating
task_struct. While the register state is a copy the rest of the FPU state
is not.
Name it accordingly and remove the really pointless @src argument along
with the warning which comes along with it.
Nothing can ever copy the FPU state of a non-current task. It's clearly
just a consequence of arch_dup_task_struct(), but it makes no sense to
proliferate that further.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121455.196727450@linutronix.de
The copy functions for the independent features are horribly named and the
supervisor and independent part is just overengineered.
The point is that the supplied mask has either to be a subset of the
independent features or a subset of the task->fpu.xstate managed features.
Rewrite it so it checks for invalid overlaps of these areas in the caller
supplied feature mask. Rename it so it follows the new naming convention
for these operations. Mop up the function documentation.
This allows to use that function for other purposes as well.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lkml.kernel.org/r/20210623121455.004880675@linutronix.de
The salient feature of "dynamic" XSTATEs is that they are not part of the
main task XSTATE buffer. The fact that they are dynamically allocated is
irrelevant and will become quite confusing when user math XSTATEs start
being dynamically allocated. Rename them to "independent" because they
are independent of the main XSTATE code.
This is just a search-and-replace with some whitespace updates to keep
things aligned.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/1eecb0e4f3e07828ebe5d737ec77dc3b708fad2d.1623388344.git.luto@kernel.org
Link: https://lkml.kernel.org/r/20210623121454.911450390@linutronix.de
The FNSAVE support requires conditionals in quite some call paths because
FNSAVE reinitializes the FPU hardware. If the save has to preserve the FPU
register state then the caller has to conditionally restore it from memory
when FNSAVE is in use.
This also requires a conditional in context switch because the restore
avoidance optimization cannot work with FNSAVE. As this only affects 20+
years old CPUs there is really no reason to keep this optimization
effective for FNSAVE. It's about time to not optimize for antiques anymore.
Just unconditionally FRSTOR the save content to the registers and clean up
the conditionals all over the place.
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121454.617369268@linutronix.de
A copy is guaranteed to leave the source intact, which is not the case when
FNSAVE is used as that reinitilizes the registers.
Save does not make such guarantees and it matches what this is about,
i.e. to save the state for a later restore.
Rename it to save_fpregs_to_fpstate().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121454.508853062@linutronix.de
copy_uabi_from_user_to_xstate() and copy_uabi_from_kernel_to_xstate() are
almost identical except for the copy function.
Unify them.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20210623121454.414215896@linutronix.de
Rename them to reflect that these functions deal with user space format
XSAVE buffers.
copy_kernel_to_xstate() -> copy_uabi_from_kernel_to_xstate()
copy_user_to_xstate() -> copy_sigframe_from_user_to_xstate()
Again a clear statement that these functions deal with user space ABI.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121454.318485015@linutronix.de
The function names for fnsave/fnrstor operations are horribly named and
a permanent source of confusion.
Rename:
copy_kernel_to_fregs() to frstor()
copy_fregs_to_user() to fnsave_to_user_sigframe()
copy_user_to_fregs() to frstor_from_user_sigframe()
so it's clear what these are doing. All these functions are really low
level wrappers around the equally named instructions, so mapping to the
documentation is just natural.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121454.223594101@linutronix.de
The function names for fxsave/fxrstor operations are horribly named and
a permanent source of confusion.
Rename:
copy_fxregs_to_kernel() to fxsave()
copy_kernel_to_fxregs() to fxrstor()
copy_fxregs_to_user() to fxsave_to_user_sigframe()
copy_user_to_fxregs() to fxrstor_from_user_sigframe()
so it's clear what these are doing. All these functions are really low
level wrappers around the equally named instructions, so mapping to the
documentation is just natural.
While at it, replace the static_cpu_has(X86_FEATURE_FXSR) with
use_fxsr() to be consistent with the rest of the code.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121454.017863494@linutronix.de
The function names for xsave[s]/xrstor[s] operations are horribly named and
a permanent source of confusion.
Rename:
copy_xregs_to_user() to xsave_to_user_sigframe()
copy_user_to_xregs() to xrstor_from_user_sigframe()
so it's entirely clear what this is about. This is also a clear indicator
of the potentially different storage format because this is user ABI and
cannot use compacted format.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.924266705@linutronix.de
The function names for xsave[s]/xrstor[s] operations are horribly named and
a permanent source of confusion.
Rename:
copy_xregs_to_kernel() to os_xsave()
copy_kernel_to_xregs() to os_xrstor()
These are truly low level wrappers around the actual instructions
XSAVE[OPT]/XRSTOR and XSAVES/XRSTORS with the twist that the selection
based on the available CPU features happens with an alternative to avoid
conditionals all over the place and to provide the best performance for hot
paths.
The os_ prefix tells that this is the OS selected mechanism.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.830239347@linutronix.de
If the fast path of restoring the FPU state on sigreturn fails or is not
taken and the current task's FPU is active then the FPU has to be
deactivated for the slow path to allow a safe update of the tasks FPU
memory state.
With supervisor states enabled, this requires to save the supervisor state
in the memory state first. Supervisor states require XSAVES so saving only
the supervisor state requires to reshuffle the memory buffer because XSAVES
uses the compacted format and therefore stores the supervisor states at the
beginning of the memory state. That's just an overengineered optimization.
Get rid of it and save the full state for this case.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.734561971@linutronix.de
The function does a sanity check with a WARN_ON_ONCE() but happily proceeds
when the pkey argument is out of range.
Clean it up.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.635764326@linutronix.de
This function is pointlessly global and a complete misnomer because it's
usage is related to both supervisor state checks and compacted format
checks. Remove it and just make the conditions check the XSAVES feature.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.425493349@linutronix.de
The only usecase for fpu__write_begin is the set() callback of regset, so
the function is pointlessly global.
Move it to the regset code and rename it to fpu_force_restore() which is
exactly decribing what the function does.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.328652975@linutronix.de
The function can only be used from the regset get() callbacks safely. So
there is no reason to have it globally exposed.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.234942936@linutronix.de
Use the new functionality of copy_xstate_to_uabi_buf() to retrieve the
FX state when XSAVE* is in use. This avoids to overwrite the FPU state
buffer with fpstate_sanitize_xstate() which is error prone and duplicated
code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.014441775@linutronix.de
Use the new functionality of copy_xstate_to_uabi_buf() to retrieve the
FX state when XSAVE* is in use. This avoids overwriting the FPU state
buffer with fpstate_sanitize_xstate() which is error prone and duplicated
code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.901736860@linutronix.de
When xsave with init state optimization is used then a component's state
in the task's xsave buffer can be stale when the corresponding feature bit
is not set.
fpregs_get() and xfpregs_get() invoke fpstate_sanitize_xstate() to update
the task's xsave buffer before retrieving the FX or FP state. That's just
duplicated code as copy_xstate_to_kernel() already handles this correctly.
Add a copy mode argument to the function which allows to restrict the state
copy to the FP and SSE features.
Also rename the function to copy_xstate_to_uabi_buf() so the name reflects
what it is doing.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.805327286@linutronix.de
fpregs_set() has unnecessary complexity to support short or nonzero-offset
writes and to handle the case in which a copy from userspace overwrites
some of the target buffer and then fails. Support for partial writes is
useless -- just require that the write has offset 0 and the correct size,
and copy into a temporary kernel buffer to avoid clobbering the state if
the user access fails.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.710467587@linutronix.de
There is no benefit from accepting and silently changing an invalid MXCSR
value supplied via ptrace(). Instead, return -EINVAL on invalid input.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.613614842@linutronix.de
xfpregs_set() was incomprehensible. Almost all of the complexity was due
to trying to support nonsensically sized writes or -EFAULT errors that
would have partially or completely overwritten the destination before
failing. Nonsensically sized input would only have been possible using
PTRACE_SETREGSET on REGSET_XFP. Fortunately, it appears (based on Debian
code search results) that no one uses that API at all, let alone with the
wrong sized buffer. Failed user access can be handled more cleanly by
first copying to kernel memory.
Just rewrite it to require sensible input.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.504234607@linutronix.de
ptrace() has interfaces that let a ptracer inspect a ptracee's register state.
This includes XSAVE state. The ptrace() ABI includes a hardware-format XSAVE
buffer for both the SETREGS and GETREGS interfaces.
In the old days, the kernel buffer and the ptrace() ABI buffer were the
same boring non-compacted format. But, since the advent of supervisor
states and the compacted format, the kernel buffer has diverged from the
format presented in the ABI.
This leads to two paths in the kernel:
1. Effectively a verbatim copy_to_user() which just copies the kernel buffer
out to userspace. This is used when the kernel buffer is kept in the
non-compacted form which means that it shares a format with the ptrace
ABI.
2. A one-state-at-a-time path: copy_xstate_to_kernel(). This is theoretically
slower since it does a bunch of piecemeal copies.
Remove the verbatim copy case. Speed probably does not matter in this path,
and the vast majority of new hardware will use the one-state-at-a-time path
anyway. This ensures greater testing for the "slow" path.
This also makes enabling PKRU in this interface easier since a single path
can be patched instead of two.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.408457100@linutronix.de
Instead of masking out reserved bits, check them and reject the provided
state as invalid if not zero.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.308388343@linutronix.de
xstateregs_set() operates on a stopped task and tries to copy the provided
buffer into the task's fpu.state.xsave buffer.
Any error while copying or invalid state detected after copying results in
wiping the target task's FPU state completely including supervisor states.
That's just wrong. The caller supplied invalid data or has a problem with
unmapped memory, so there is absolutely no justification to corrupt the
target state.
Fix this with the following modifications:
1) If data has to be copied from userspace, allocate a buffer and copy from
user first.
2) Use copy_kernel_to_xstate() unconditionally so that header checking
works correctly.
3) Return on error without corrupting the target state.
This prevents corrupting states and lets the caller deal with the problem
it caused in the first place.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.214903673@linutronix.de
If the count argument is larger than the xstate size, this will happily
copy beyond the end of xstate.
Fixes: 91c3dba7db ("x86/fpu/xstate: Fix PTRACE frames for XSAVES")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.120741557@linutronix.de
They are only used in fpstate_init() and there is no point to have them in
a header just to make reading the code harder.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.023118522@linutronix.de
Thomas Gleixner