I recently spent some extra time debugging a false positive because I
didn't realize the "real" tag was in the short granule. Adding the
short tag here makes it more obvious that we could be dealing with a
short granule.
Reviewed By: hctim, eugenis
Differential Revision: https://reviews.llvm.org/D112949
The shadow for a short granule is stored in the last byte of the
granule. Currently, if there's a tail-overwrite report (a
buffer-overflow-write in uninstrumented code), we report the shadow byte
as a mismatch against the magic.
Fix this bug by slapping the shadow into the expected value. This also
makes sure that if the uninstrumented WRITE does clobber the shadow
byte, it reports the shadow was actually clobbered as well.
Reviewed By: eugenis, fmayer
Differential Revision: https://reviews.llvm.org/D107938
We would find an address with matching tag, only to discover in
ShowCandidate that it's very far away from [stack].
Reviewed By: eugenis
Differential Revision: https://reviews.llvm.org/D105197
If the fault address is at the boundary of memory regions, this could
cause us to segfault otherwise.
Ran test with old compiler_rt to make sure it fails.
Reviewed By: eugenis
Differential Revision: https://reviews.llvm.org/D105032
A heap or global buffer that is far away from the faulting address is
unlikely to be the cause, especially if there is a potential
use-after-free as well, so we want to show it after the other
causes.
Reviewed By: eugenis
Differential Revision: https://reviews.llvm.org/D104781
Explain what the given stack trace means before showing it, rather than
only in the paragraph at the end.
Reviewed By: eugenis
Differential Revision: https://reviews.llvm.org/D104523
Before: ADDR is located -320 bytes to the right of 1072-byte region
After: ADDR is located 752 bytes inside 1072-byte region
Reviewed By: eugenis, walli99
Differential Revision: https://reviews.llvm.org/D104412
InternalScopedString uses InternalMmapVector internally
so it can be resized dynamically as needed.
Reviewed By: eugenis
Differential Revision: https://reviews.llvm.org/D98751
Similar to __asan_set_error_report_callback, pass the entire report to a
user provided callback function.
Differential Revision: https://reviews.llvm.org/D91825
In `GetGlobalSizeFromDescriptor` we use `dladdr` to get info on the the
current address. `dladdr` returns 0 if it failed.
During testing on Linux this returned 0 to indicate failure, and
populated the `info` structure with a NULL pointer which was
dereferenced later.
This patch checks for `dladdr` returning 0, and in that case returns 0
from `GetGlobalSizeFromDescriptor` to indicate failure of identifying
the address.
This occurs when `GetModuleNameAndOffsetForPC` succeeds for some address
not in a dynamically loaded library. One example is when the found
"module" is '[stack]' having come from parsing /proc/self/maps.
Differential Revision: https://reviews.llvm.org/D91344
Adds a check to avoid symbolization when printing stack traces if the
stack_trace_format flag does not need it. While there is a symbolize
flag that can be turned off to skip some of the symbolization,
SymbolizePC() still unconditionally looks up the module name and offset.
Avoid invoking SymbolizePC() at all if not needed.
This is an efficiency improvement when dumping all stack traces as part
of the memory profiler in D87120, for large stripped apps where we want
to symbolize as a post pass.
Differential Revision: https://reviews.llvm.org/D88361
Summary: Refactor the current global header iteration to be callback-based, and add a feature that reports the size of the global variable during reporting. This allows binaries without symbols to still report the size of the global variable, which is always available in the HWASan globals PT_NOTE metadata.
Reviewers: eugenis, pcc
Reviewed By: pcc
Subscribers: mgorny, llvm-commits, #sanitizers
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D80599
Shadow memory (and short granules) are not prepended with memory
address and arrow at the end of line is removed.
Differential Revision: https://reviews.llvm.org/D70707
Globals are instrumented by adding a pointer tag to their symbol values
and emitting metadata into a special section that allows the runtime to tag
their memory when the library is loaded.
Due to order of initialization issues explained in more detail in the comments,
shadow initialization cannot happen during regular global initialization.
Instead, the location of the global section is marked using an ELF note,
and we require libc support for calling a function provided by the HWASAN
runtime when libraries are loaded and unloaded.
Based on ideas discussed with @evgeny777 in D56672.
Differential Revision: https://reviews.llvm.org/D65770
llvm-svn: 368102
A short granule is a granule of size between 1 and `TG-1` bytes. The size
of a short granule is stored at the location in shadow memory where the
granule's tag is normally stored, while the granule's actual tag is stored
in the last byte of the granule. This means that in order to verify that a
pointer tag matches a memory tag, HWASAN must check for two possibilities:
* the pointer tag is equal to the memory tag in shadow memory, or
* the shadow memory tag is actually a short granule size, the value being loaded
is in bounds of the granule and the pointer tag is equal to the last byte of
the granule.
Pointer tags between 1 to `TG-1` are possible and are as likely as any other
tag. This means that these tags in memory have two interpretations: the full
tag interpretation (where the pointer tag is between 1 and `TG-1` and the
last byte of the granule is ordinary data) and the short tag interpretation
(where the pointer tag is stored in the granule).
When HWASAN detects an error near a memory tag between 1 and `TG-1`, it
will show both the memory tag and the last byte of the granule. Currently,
it is up to the user to disambiguate the two possibilities.
Because this functionality obsoletes the right aligned heap feature of
the HWASAN memory allocator (and because we can no longer easily test
it), the feature is removed.
Also update the documentation to cover both short granule tags and
outlined checks.
Differential Revision: https://reviews.llvm.org/D63908
llvm-svn: 365551
Each function's PC is recorded in the ring buffer. From there we can access
the function's local variables and reconstruct the tag of each one with the
help of the information printed by llvm-symbolizer's new FRAME command. We
can then find the variable that was likely being accessed by matching the
pointer's tag against the reconstructed tag.
Differential Revision: https://reviews.llvm.org/D63469
llvm-svn: 364607
Summary:
Explicitly print 4 registers/line in each iteration during register
dump. Reduces logcat spam as we get a single logcat message per call to
Printf(), even if the output isn't newline-terminated. This brings the
output format in logcat closer to that of the normal textual dump.
Reviewers: eugenis, pcc
Reviewed By: pcc
Subscribers: kubamracek, #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D59320
llvm-svn: 356166
Summary:
This change change the instrumentation to allow users to view the registers at the point at which tag mismatch occured. Most of the heavy lifting is done in the runtime library, where we save the registers to the stack and emit unwind information. This allows us to reduce the overhead, as very little additional work needs to be done in each __hwasan_check instance.
In this implementation, the fast path of __hwasan_check is unmodified. There are an additional 4 instructions (16B) emitted in the slow path in every __hwasan_check instance. This may increase binary size somewhat, but as most of the work is done in the runtime library, it's manageable.
The failure trace now contains a list of registers at the point of which the failure occured, in a format similar to that of Android's tombstones. It currently has the following format:
Registers where the failure occurred (pc 0x0055555561b4):
x0 0000000000000014 x1 0000007ffffff6c0 x2 1100007ffffff6d0 x3 12000056ffffe025
x4 0000007fff800000 x5 0000000000000014 x6 0000007fff800000 x7 0000000000000001
x8 12000056ffffe020 x9 0200007700000000 x10 0200007700000000 x11 0000000000000000
x12 0000007fffffdde0 x13 0000000000000000 x14 02b65b01f7a97490 x15 0000000000000000
x16 0000007fb77376b8 x17 0000000000000012 x18 0000007fb7ed6000 x19 0000005555556078
x20 0000007ffffff768 x21 0000007ffffff778 x22 0000000000000001 x23 0000000000000000
x24 0000000000000000 x25 0000000000000000 x26 0000000000000000 x27 0000000000000000
x28 0000000000000000 x29 0000007ffffff6f0 x30 00000055555561b4
... and prints after the dump of memory tags around the buggy address.
Every register is saved exactly as it was at the point where the tag mismatch occurs, with the exception of x16/x17. These registers are used in the tag mismatch calculation as scratch registers during __hwasan_check, and cannot be saved without affecting the fast path. As these registers are designated as scratch registers for linking, there should be no important information in them that could aid in debugging.
Reviewers: pcc, eugenis
Reviewed By: pcc, eugenis
Subscribers: srhines, kubamracek, mgorny, javed.absar, krytarowski, kristof.beyls, hiraditya, jdoerfert, llvm-commits, #sanitizers
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D58857
llvm-svn: 355738
As discussed elsewhere: LLVM uses cpp as its C++ source extension; the
sanitizers should too. This updates files in hwasan.
Patch generated by
for f in lib/hwasan/*.cc ; do svn mv $f ${f%.cc}.cpp; done
followed by
for f in lib/hwasan/*.cpp ; do sed -i '' -e '1s/\.cc -/.cpp /' $f; done
CMakeLists.txt updated manually.
Differential Revision: https://reviews.llvm.org/D58620
llvm-svn: 354989
Martin Liska