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| author | Jann Horn <jannh@google.com> | 2019-07-16 17:20:45 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-07-25 15:37:04 +0200 |
| commit | 16d51a590a8ce3befb1308e0e7ab77f3b661af33 (patch) | |
| tree | e147b1ad1061369a9fd8546aa18ef519474d2fc2 /kernel/fork.c | |
| parent | 7b5cf701ea9c395c792e2a7e3b7caf4c68b87721 (diff) | |
| download | linux-16d51a590a8ce3befb1308e0e7ab77f3b661af33.tar.gz linux-16d51a590a8ce3befb1308e0e7ab77f3b661af33.tar.bz2 linux-16d51a590a8ce3befb1308e0e7ab77f3b661af33.zip | |
sched/fair: Don't free p->numa_faults with concurrent readers
When going through execve(), zero out the NUMA fault statistics instead of
freeing them.
During execve, the task is reachable through procfs and the scheduler. A
concurrent /proc/*/sched reader can read data from a freed ->numa_faults
allocation (confirmed by KASAN) and write it back to userspace.
I believe that it would also be possible for a use-after-free read to occur
through a race between a NUMA fault and execve(): task_numa_fault() can
lead to task_numa_compare(), which invokes task_weight() on the currently
running task of a different CPU.
Another way to fix this would be to make ->numa_faults RCU-managed or add
extra locking, but it seems easier to wipe the NUMA fault statistics on
execve.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Fixes: 82727018b0d3 ("sched/numa: Call task_numa_free() from do_execve()")
Link: https://lkml.kernel.org/r/20190716152047.14424-1-jannh@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index d8ae0f1b4148..2852d0e76ea3 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -726,7 +726,7 @@ void __put_task_struct(struct task_struct *tsk) WARN_ON(tsk == current); cgroup_free(tsk); - task_numa_free(tsk); + task_numa_free(tsk, true); security_task_free(tsk); exit_creds(tsk); delayacct_tsk_free(tsk); |