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authorJann Horn <jannh@google.com>2019-07-16 17:20:45 +0200
committerIngo Molnar <mingo@kernel.org>2019-07-25 15:37:04 +0200
commit16d51a590a8ce3befb1308e0e7ab77f3b661af33 (patch)
treee147b1ad1061369a9fd8546aa18ef519474d2fc2 /fs/exec.c
parent7b5cf701ea9c395c792e2a7e3b7caf4c68b87721 (diff)
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 'fs/exec.c')
-rw-r--r--fs/exec.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/exec.c b/fs/exec.c
index c71cbfe6826a..f7f6a140856a 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1828,7 +1828,7 @@ static int __do_execve_file(int fd, struct filename *filename,
membarrier_execve(current);
rseq_execve(current);
acct_update_integrals(current);
- task_numa_free(current);
+ task_numa_free(current, false);
free_bprm(bprm);
kfree(pathbuf);
if (filename)