If an attacker can cause a controlled kernel stack overflow, overwriting
the restart block is a very juicy exploit target. This is because the
restart_block is held in the same memory allocation as the kernel stack.
Moving the restart block to struct task_struct prevents this exploit by
making the restart_block harder to locate.
Note that there are other fields in thread_info that are also easy
targets, at least on some architectures.
It's also a decent simplification, since the restart code is more or less
identical on all architectures.
[james.hogan@imgtec.com: metag: align thread_info::supervisor_stack]
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Miller <davem@davemloft.net>
Acked-by: Richard Weinberger <richard@nod.at>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use compat_sigset_t rather than opencode the array
Drop "switch (_NSIG_WORDS)" as we know this is always 1
Introduce BUILD_BUG_ON() to catch if this changes
As a side-effect of this fix following sparse warnings:
signal32.c:220:60: warning: invalid access past the end of 'seta' (12 8)
signal32.c:220:42: warning: invalid access past the end of 'seta' (8 8)
signal32.c:219:60: warning: invalid access past the end of 'seta' (20 8)
signal32.c:219:42: warning: invalid access past the end of 'seta' (16 8)
signal32.c:218:60: warning: invalid access past the end of 'seta' (28 8)
signal32.c:218:42: warning: invalid access past the end of 'seta' (24 8)
signal32.c:309:68: warning: invalid access past the end of 'seta' (12 8)
signal32.c:309:46: warning: invalid access past the end of 'seta' (8 8)
signal32.c:308:68: warning: invalid access past the end of 'seta' (20 8)
signal32.c:308:46: warning: invalid access past the end of 'seta' (16 8)
signal32.c:307:68: warning: invalid access past the end of 'seta' (28 8)
signal32.c:307:46: warning: invalid access past the end of 'seta' (24 8)
They all pointed to code that was never executed - so no bugs fixed.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix following warnings:
signal32.c:140:6: warning: symbol 'do_sigreturn32' was not declared. Should it be static?
signal32.c:230:17: warning: symbol 'do_rt_sigreturn32' was not declared. Should it be static?
signal32.c:729:6: warning: symbol 'do_signal32' was not declared. Should it be static?
signal32.c:773:16: warning: symbol 'do_sys32_sigstack' was not declared. Should it be static?
Add proper prototypes and drop local prototype
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is a preparatory patch for the introduction of NT_SIGINFO elf note.
Make the location of compat_siginfo_t uniform across eight architectures
which have it. Now it can be pulled in by including asm/compat.h or
linux/compat.h.
Most of the copies are verbatim. compat_uid[32]_t had to be replaced by
__compat_uid[32]_t. compat_uptr_t had to be moved up before
compat_siginfo_t in asm/compat.h on a several architectures (tile already
had it moved up). compat_sigval_t had to be relocated from linux/compat.h
to asm/compat.h.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Amerigo Wang <amwang@redhat.com>
Cc: "Jonathan M. Foote" <jmfoote@cert.org>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Does block_sigmask() + tracehook_signal_handler(); called when
sigframe has been successfully built. All architectures converted
to it; block_sigmask() itself is gone now (merged into this one).
I'm still not too happy with the signature, but that's a separate
story (IMO we need a structure that would contain signal number +
siginfo + k_sigaction, so that get_signal_to_deliver() would fill one,
signal_delivered(), handle_signal() and probably setup...frame() -
take one).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Only 3 out of 63 do not. Renamed the current variant to __set_current_blocked(),
added set_current_blocked() that will exclude unblockable signals, switched
open-coded instances to it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
first fruits of ..._restore_sigmask() helpers: now we can take
boilerplate "signal didn't have a handler, clear RESTORE_SIGMASK
and restore the blocked mask from ->saved_mask" into a common
helper. Open-coded instances switched...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Use the new helper function introduced in commit 5e6292c0f2 ("signal:
add block_sigmask() for adding sigmask to current->blocked") which
centralises the code for updating current->blocked after successfully
delivering a signal and reduces the amount of duplicate code across
architectures. In the past some architectures got this code wrong, so
using this helper function should stop that from happening again.
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As per the comments added by this commit, %g2 turns out to not be a
usable place to save away orig_i0 for syscall restart handling.
In fact all of %g2, %g3, %g4, and %g5 are assumed to be saved across
a system call by various bits of code in glibc.
%g1 can't be used because that holds the syscall number, which would
need to be saved and restored for syscall restart handling too, and
that would only compound our problems :-)
This leaves us with %g6 and %g7 which are for "system use". %g7 is
used as the "thread register" by glibc, but %g6 is used as a compiler
and assembler temporary scratch register. And in no instance is %g6
used to hold a value across a system call.
Therefore %g6 is safe for storing away orig_i0, at least for now.
Signed-off-by: David S. Miller <davem@davemloft.net>
Although we provide a proper way for a debugger to control whether
syscall restart occurs, we run into problems because orig_i0 is not
saved and restored properly.
Luckily we can solve this problem without having to make debuggers
aware of the issue. Across system calls, several registers are
considered volatile and can be safely clobbered.
Therefore we use the pt_regs save area of one of those registers, %g2,
as a place to save and restore orig_i0.
Debuggers transparently will do the right thing because they save and
restore this register already.
Signed-off-by: David S. Miller <davem@davemloft.net>
As described in e6fa16ab ("signal: sigprocmask() should do
retarget_shared_pending()") the modification of current->blocked is
incorrect as we need to check whether the signal we're about to block
is pending in the shared queue.
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If we can't push the pending register windows onto the user's stack,
we disallow signal delivery even if the signal would be delivered on a
valid seperate signal stack.
Add a register window save area in the signal frame, and store any
unsavable windows there.
On sigreturn, if any windows are still queued up in the signal frame,
try to push them back onto the stack and if that fails we kill the
process immediately.
This allows the debug/tst-longjmp_chk2 glibc test case to pass.
Signed-off-by: David S. Miller <davem@davemloft.net>
Explicitly clear the "in-syscall" bit when we have no signal
handler and back up the program counters to back up the system
call.
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Don't invoke the signal handler tracehook in that situation
either.
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
If another cpu does a very wide munmap() on the signal frame area,
it can tear down the page table hierarchy from underneath us.
Borrow an idea from the 64-bit fault path's get_user_insn(), and
disable cross call interrupts during the page table traversal
to lock them in place while we operate.
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is mandatory for 64-bit processes, and doing it also for 32-bit
processes saves a conditional in the compat case.
This fixes the glibc/nptl/tst-stdio1 test case, as well
as many others, on 64-bit.
Signed-off-by: David S. Miller <davem@davemloft.net>
o Move all files from sparc64/kernel/ to sparc/kernel
- rename as appropriate
o Update sparc/Makefile to the changes
o Update sparc/kernel/Makefile to include the sparc64 files
NOTE: This commit changes link order on sparc64!
Link order had to change for either of sparc32 and sparc64.
And assuming sparc64 see more testing than sparc32 change link
order on sparc64 where issues will be caught faster.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Andy Lutomirski