Revision 399f8dd9a866e107639eabd3c1979cd526ca3a98 authored by Thomas Gleixner on 21 June 2021, 23:08:30 UTC, committed by Thomas Gleixner on 22 June 2021, 13:55:41 UTC
syzbot reported a memory leak related to sigqueue caching. The assumption that a task cannot cache a sigqueue after the signal handler has been dropped and exit_task_sigqueue_cache() has been invoked turns out to be wrong. Such a task can still invoke release_task(other_task), which cleans up the signals of 'other_task' and ends up in sigqueue_cache_or_free(), which in turn will cache the signal because task->sigqueue_cache is NULL. That's obviously bogus because nothing will free the cached signal of that task anymore, so the cached item is leaked. This happens when e.g. the last non-leader thread exits and reaps the zombie leader. Prevent this by setting tsk::sigqueue_cache to an error pointer value in exit_task_sigqueue_cache() which forces any subsequent invocation of sigqueue_cache_or_free() from that task to hand the sigqueue back to the kmemcache. Add comments to all relevant places. Fixes: 4bad58ebc8bc ("signal: Allow tasks to cache one sigqueue struct") Reported-by: syzbot+0bac5fec63d4f399ba98@syzkaller.appspotmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/878s32g6j5.ffs@nanos.tec.linutronix.de
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LICENSES | ||
arch | ||
block | ||
certs | ||
crypto | ||
drivers | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | -rw-r--r-- | 16.6 KB |
.cocciconfig | -rw-r--r-- | 59 bytes |
.get_maintainer.ignore | -rw-r--r-- | 71 bytes |
.gitattributes | -rw-r--r-- | 62 bytes |
.gitignore | -rw-r--r-- | 1.9 KB |
.mailmap | -rw-r--r-- | 19.5 KB |
COPYING | -rw-r--r-- | 496 bytes |
CREDITS | -rw-r--r-- | 98.6 KB |
Kbuild | -rw-r--r-- | 1.3 KB |
Kconfig | -rw-r--r-- | 555 bytes |
MAINTAINERS | -rw-r--r-- | 588.5 KB |
Makefile | -rw-r--r-- | 64.4 KB |
README | -rw-r--r-- | 727 bytes |
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