c6a690e0c9
KASAN suppresses reports for bad accesses done by the KASAN reporting
code. The reporting code might access poisoned memory for reporting
purposes.
Software KASAN modes do this by suppressing reports during reporting via
current->kasan_depth, the same way they suppress reports during accesses
to poisoned slab metadata.
Hardware Tag-Based KASAN does not use current->kasan_depth, and instead
resets pointer tags for accesses to poisoned memory done by the reporting
code.
Despite that, a recursive report can still happen:
1. On hardware with faulty MTE support. This was observed by Weizhao
Ouyang on a faulty hardware that caused memory tags to randomly change
from time to time.
2. Theoretically, due to a previous MTE-undetected memory corruption.
A recursive report can happen via:
1. Accessing a pointer with a non-reset tag in the reporting code, e.g.
slab->slab_cache, which is what Weizhao Ouyang observed.
2. Theoretically, via external non-annotated routines, e.g. stackdepot.
To resolve this issue, resetting tags for all of the pointers in the
reporting code and all the used external routines would be impractical.
Instead, disable tag checking done by the CPU for the duration of KASAN
reporting for Hardware Tag-Based KASAN.
Without this fix, Hardware Tag-Based KASAN reporting code might deadlock.
[andreyknvl@google.com: disable preemption instead of migration, fix comment typo]
Link: https://lkml.kernel.org/r/d14417c8bc5eea7589e99381203432f15c0f9138.1680114854.git.andreyknvl@google.com
Link: https://lkml.kernel.org/r/59f433e00f7fa985e8bf9f7caf78574db16b67ab.1678491668.git.andreyknvl@google.com
Fixes:
|
||
|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.