https://github.com/torvalds/linux
Revision 6376360ecbe525a9c17b3d081dfd88ba3e4ed65b authored by Naoya Horiguchi on 01 February 2019, 22:21:08 UTC, committed by Linus Torvalds on 01 February 2019, 23:46:23 UTC
Currently memory_failure() is racy against process's exiting, which results in kernel crash by null pointer dereference. The root cause is that memory_failure() uses force_sig() to forcibly kill asynchronous (meaning not in the current context) processes. As discussed in thread https://lkml.org/lkml/2010/6/8/236 years ago for OOM fixes, this is not a right thing to do. OOM solves this issue by using do_send_sig_info() as done in commit d2d393099de2 ("signal: oom_kill_task: use SEND_SIG_FORCED instead of force_sig()"), so this patch is suggesting to do the same for hwpoison. do_send_sig_info() properly accesses to siglock with lock_task_sighand(), so is free from the reported race. I confirmed that the reported bug reproduces with inserting some delay in kill_procs(), and it never reproduces with this patch. Note that memory_failure() can send another type of signal using force_sig_mceerr(), and the reported race shouldn't happen on it because force_sig_mceerr() is called only for synchronous processes (i.e. BUS_MCEERR_AR happens only when some process accesses to the corrupted memory.) Link: http://lkml.kernel.org/r/20190116093046.GA29835@hori1.linux.bs1.fc.nec.co.jp Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Jane Chu <jane.chu@oracle.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 0d0c8de
Tip revision: 6376360ecbe525a9c17b3d081dfd88ba3e4ed65b authored by Naoya Horiguchi on 01 February 2019, 22:21:08 UTC
mm: hwpoison: use do_send_sig_info() instead of force_sig()
mm: hwpoison: use do_send_sig_info() instead of force_sig()
Tip revision: 6376360
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certs | ||
crypto | ||
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kernel | ||
lib | ||
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.cocciconfig | -rw-r--r-- | 59 bytes |
.get_maintainer.ignore | -rw-r--r-- | 31 bytes |
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.mailmap | -rw-r--r-- | 10.7 KB |
COPYING | -rw-r--r-- | 423 bytes |
CREDITS | -rw-r--r-- | 96.9 KB |
Kbuild | -rw-r--r-- | 1.7 KB |
Kconfig | -rw-r--r-- | 563 bytes |
MAINTAINERS | -rw-r--r-- | 481.4 KB |
Makefile | -rw-r--r-- | 59.1 KB |
README | -rw-r--r-- | 727 bytes |
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