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4b4d2c7992
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Eric W. Biederman 4b4d2c7992 coredump: Limit what can interrupt coredumps 
[ Upstream commit 06af867944 ]

Olivier Langlois has been struggling with coredumps being incompletely written in
processes using io_uring.

Olivier Langlois <olivier@trillion01.com> writes:
> io_uring is a big user of task_work and any event that io_uring made a
> task waiting for that occurs during the core dump generation will
> generate a TIF_NOTIFY_SIGNAL.
>
> Here are the detailed steps of the problem:
> 1. io_uring calls vfs_poll() to install a task to a file wait queue
>    with io_async_wake() as the wakeup function cb from io_arm_poll_handler()
> 2. wakeup function ends up calling task_work_add() with TWA_SIGNAL
> 3. task_work_add() sets the TIF_NOTIFY_SIGNAL bit by calling
>    set_notify_signal()

The coredump code deliberately supports being interrupted by SIGKILL,
and depends upon prepare_signal to filter out all other signals.   Now
that signal_pending includes wake ups for TIF_NOTIFY_SIGNAL this hack
in dump_emitted by the coredump code no longer works.

Make the coredump code more robust by explicitly testing for all of
the wakeup conditions the coredump code supports.  This prevents
new wakeup conditions from breaking the coredump code, as well
as fixing the current issue.

The filesystem code that the coredump code uses already limits
itself to only aborting on fatal_signal_pending.  So it should
not develop surprising wake-up reasons either.

v2: Don't remove the now unnecessary code in prepare_signal.

Cc: stable@vger.kernel.org
Fixes: 12db8b6900 ("entry: Add support for TIF_NOTIFY_SIGNAL")
Reported-by: Olivier Langlois <olivier@trillion01.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-04 11:39:22 +01:00
arch alpha: fix TIF_NOTIFY_SIGNAL handling 2023-01-04 11:39:22 +01:00
block block: unhash blkdev part inode when the part is deleted 2022-12-08 11:23:59 +01:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:13:17 +02:00
crypto crypto: akcipher - default implementation for setting a private key 2022-10-26 13:25:42 +02:00
Documentation docs: update mediator contact information in CoC doc 2022-11-25 17:45:53 +01:00
drivers file: Rename __close_fd_get_file close_fd_get_file 2023-01-04 11:39:18 +01:00
fs coredump: Limit what can interrupt coredumps 2023-01-04 11:39:22 +01:00
include kernel: remove checking for TIF_NOTIFY_SIGNAL 2023-01-04 11:39:22 +01:00
init init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash 2022-12-02 17:40:03 +01:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:24:00 +01:00
kernel kernel: remove checking for TIF_NOTIFY_SIGNAL 2023-01-04 11:39:22 +01:00
lib iov_iter: add helper to save iov_iter state 2023-01-04 11:39:16 +01:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/hugetlb: fix races when looking up a CONT-PTE/PMD size hugetlb page 2022-12-14 11:31:59 +01:00
net net: add accept helper not installing fd 2023-01-04 11:39:17 +01:00
samples x86: Prepare inline-asm for straight-line-speculation 2022-07-25 11:26:29 +02:00
scripts scripts/faddr2line: Fix regression in name resolution on ppc64le 2022-12-08 11:23:54 +01:00
security capabilities: fix potential memleak on error path from vfs_getxattr_alloc() 2022-11-10 18:14:26 +01:00
sound ASoC: ops: Correct bounds check for second channel on SX controls 2022-12-19 12:27:32 +01:00
tools tools headers UAPI: Sync openat2.h with the kernel sources 2023-01-04 11:39:17 +01:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:25:48 +01:00
virt kvm: Add support for arch compat vm ioctls 2022-10-30 09:41:15 +01:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add Amir as xfs maintainer for 5.10.y 2022-07-02 16:39:22 +02:00
Makefile Linux 5.10.161 2022-12-21 17:32:08 +01:00
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.