Linux mainline fork with MSM8998 patches | https://mainline.space | Currently supported devices:
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efd608fa74
I encountered some occasional crashes of poke_int3_handler() when
kprobes are set, while accessing desc->vec.
The text poke mechanism claims to have an RCU-like behavior, but it
does not appear that there is any quiescent state to ensure that
nobody holds reference to desc. As a result, the following race
appears to be possible, which can lead to memory corruption.
CPU0 CPU1
---- ----
text_poke_bp_batch()
-> smp_store_release(&bp_desc, &desc)
[ notice that desc is on
the stack ]
poke_int3_handler()
[ int3 might be kprobe's
so sync events are do not
help ]
-> try_get_desc(descp=&bp_desc)
desc = __READ_ONCE(bp_desc)
if (!desc) [false, success]
WRITE_ONCE(bp_desc, NULL);
atomic_dec_and_test(&desc.refs)
[ success, desc space on the stack
is being reused and might have
non-zero value. ]
arch_atomic_inc_not_zero(&desc->refs)
[ might succeed since desc points to
stack memory that was freed and might
be reused. ]
Fix this issue with small backportable patch. Instead of trying to
make RCU-like behavior for bp_desc, just eliminate the unnecessary
level of indirection of bp_desc, and hold the whole descriptor as a
global. Anyhow, there is only a single descriptor at any given
moment.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.