Said function had a few shortfalls:
- didn't set an abort message on Android
- was logged on several lines
- didn't provide extra information like the size requested if OOM'ing
This improves the function to address those points.
Differential Revision: https://reviews.llvm.org/D103034
This patch enhances the secondary allocator to be able to detect buffer
overflow, and (on hardware supporting memory tagging) use-after-free
and buffer underflow.
Use-after-free detection is implemented by setting memory page
protection to PROT_NONE on free. Because this must be done immediately
rather than after the memory has been quarantined, we no longer use the
combined allocator quarantine for secondary allocations. Instead, a
quarantine has been added to the secondary allocator cache.
Buffer overflow detection is implemented by aligning the allocation
to the right of the writable pages, so that any overflows will
spill into the guard page to the right of the allocation, which
will have PROT_NONE page protection. Because this would require the
secondary allocator to produce a header at the correct position,
the responsibility for ensuring chunk alignment has been moved to
the secondary allocator.
Buffer underflow detection has been implemented on hardware supporting
memory tagging by tagging the memory region between the start of the
mapping and the start of the allocation with a non-zero tag. Due to
the cost of pre-tagging secondary allocations and the memory bandwidth
cost of tagged accesses, the allocation itself uses a tag of 0 and
only the first four pages have memory tagging enabled.
This is a reland of commit 7a0da88943 which was reverted in commit
9678b07e42. This reland includes the following changes:
- Fix the calculation of BlockSize which led to incorrect statistics
returned by mallinfo().
- Add -Wno-pedantic to silence GCC warning.
- Optionally add some slack at the end of secondary allocations to help
work around buggy applications that read off the end of their
allocation.
Differential Revision: https://reviews.llvm.org/D93731
This patch enhances the secondary allocator to be able to detect buffer
overflow, and (on hardware supporting memory tagging) use-after-free
and buffer underflow.
Use-after-free detection is implemented by setting memory page
protection to PROT_NONE on free. Because this must be done immediately
rather than after the memory has been quarantined, we no longer use the
combined allocator quarantine for secondary allocations. Instead, a
quarantine has been added to the secondary allocator cache.
Buffer overflow detection is implemented by aligning the allocation
to the right of the writable pages, so that any overflows will
spill into the guard page to the right of the allocation, which
will have PROT_NONE page protection. Because this would require the
secondary allocator to produce a header at the correct position,
the responsibility for ensuring chunk alignment has been moved to
the secondary allocator.
Buffer underflow detection has been implemented on hardware supporting
memory tagging by tagging the memory region between the start of the
mapping and the start of the allocation with a non-zero tag. Due to
the cost of pre-tagging secondary allocations and the memory bandwidth
cost of tagged accesses, the allocation itself uses a tag of 0 and
only the first four pages have memory tagging enabled.
Differential Revision: https://reviews.llvm.org/D93731
Kernel support for MTE has been released in Linux 5.10. This means
that it is a stable API and we no longer need to make the support
conditional on a macro. We do need to provide conditional definitions
of the new macros though in order to avoid a dependency on new
kernel headers.
Differential Revision: https://reviews.llvm.org/D93513
Introduce a function __scudo_get_error_info() that may be called to interpret
a crash resulting from a memory error, potentially in another process,
given information extracted from the crashing process. The crash may be
interpreted as a use-after-free, buffer overflow or buffer underflow.
Also introduce a feature to optionally record a stack trace for each
allocation and deallocation. If this feature is enabled, a stack trace for
the allocation and (if applicable) the deallocation will also be available
via __scudo_get_error_info().
Differential Revision: https://reviews.llvm.org/D77283
Summary:
The function used to log on Android will cut the message past
a certain amount of characters, which mostly materializes when
dumping the size class map on OOM.
This change splits the log message at newline boundaries.
Reviewers: pcc, cferris, hctim, eugenis
Subscribers: #sanitizers, llvm-commits
Tags: #sanitizers
Differential Revision: https://reviews.llvm.org/D78018
Summary:
Zygote & children's stderr is lost, so use Bionic's provided allocation
free syslog function for `outputRaw`. Get rid of the mutex as it's not
vital and could cause issues with `fork`.
Reviewers: cferris, pcc, eugenis, hctim, morehouse
Subscribers: #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D73561
Summary:
In some configuration, `sched_getaffinity` can fail. Some reasons for
that being the lack of `CAP_SYS_NICE` capability or some syscall
filtering and so on.
This should not be fatal to the allocator, so in this situation, we
will fallback to the `MaxTSDCount` value specified in the allocator
configuration.
Reviewers: cferris, eugenis, hctim, morehouse, pcc
Subscribers: #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D73055
When the hardware and operating system support the ARM Memory Tagging
Extension, tag primary allocation granules with a random tag. The granules
either side of the allocation are tagged with tag 0, which is normally
excluded from the set of tags that may be selected randomly. Memory is
also retagged with a random tag when it is freed, and we opportunistically
reuse the new tag when the block is reused to reduce overhead. This causes
linear buffer overflows to be caught deterministically and non-linear buffer
overflows and use-after-free to be caught probabilistically.
This feature is currently only enabled for the Android allocator
and depends on an experimental Linux kernel branch available here:
https://github.com/pcc/linux/tree/android-experimental-mte
All code that depends on the kernel branch is hidden behind a macro,
ANDROID_EXPERIMENTAL_MTE. This is the same macro that is used by the Android
platform and may only be defined in non-production configurations. When the
userspace interface is finalized the code will be updated to use the stable
interface and all #ifdef ANDROID_EXPERIMENTAL_MTE will be removed.
Differential Revision: https://reviews.llvm.org/D70762
Summary:
Few corrections with no functional change:
- replacing `%zd` with `%zu` all around: the values are unsigned
- prefer `MAP_ANONYMOUS` to `MAP_ANON` (it's deprecated)
- remove the unused `enum LinkerInitialized`
- mark a parameter as `UNUSED` in Fuchsia's `getRandom`
- correct the casing of a variable and use `nullptr` instead of 0 for
pointers in `list.h`
- reorder some `typedef` to be consistent between `signed` and
`unsigned`
Reviewers: eugenis, vitalybuka, morehouse, hctim
Reviewed By: vitalybuka, morehouse
Subscribers: delcypher, #sanitizers, llvm-commits
Tags: #llvm, #sanitizers
Differential Revision: https://reviews.llvm.org/D65660
llvm-svn: 368585
Alex Brachet