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authorPeter Zijlstra <peterz@infradead.org>2014-10-02 16:17:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-10-02 16:28:44 -0700
commit6c72e3501d0d62fc064d3680e5234f3463ec5a86 (patch)
tree48b15a8bc67816fe492e1323580bf8ee99b29e81
parentcba5b1c6e2c42152135a85b90bf820b77d6527da (diff)
downloadlinux-6c72e3501d0d62fc064d3680e5234f3463ec5a86.tar.gz
perf: fix perf bug in fork()
Oleg noticed that a cleanup by Sylvain actually uncovered a bug; by calling perf_event_free_task() when failing sched_fork() we will not yet have done the memset() on ->perf_event_ctxp[] and will therefore try and 'free' the inherited contexts, which are still in use by the parent process. This is bad.. Suggested-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Sylvain 'ythier' Hitier <sylvain.hitier@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/events/core.c4
-rw-r--r--kernel/fork.c5
2 files changed, 6 insertions, 3 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index d640a8b4dcbc..963bf139e2b2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7948,8 +7948,10 @@ int perf_event_init_task(struct task_struct *child)
for_each_task_context_nr(ctxn) {
ret = perf_event_init_context(child, ctxn);
- if (ret)
+ if (ret) {
+ perf_event_free_task(child);
return ret;
+ }
}
return 0;
diff --git a/kernel/fork.c b/kernel/fork.c
index 0cf9cdb6e491..a91e47d86de2 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1360,7 +1360,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
goto bad_fork_cleanup_policy;
retval = audit_alloc(p);
if (retval)
- goto bad_fork_cleanup_policy;
+ goto bad_fork_cleanup_perf;
/* copy all the process information */
shm_init_task(p);
retval = copy_semundo(clone_flags, p);
@@ -1566,8 +1566,9 @@ bad_fork_cleanup_semundo:
exit_sem(p);
bad_fork_cleanup_audit:
audit_free(p);
-bad_fork_cleanup_policy:
+bad_fork_cleanup_perf:
perf_event_free_task(p);
+bad_fork_cleanup_policy:
#ifdef CONFIG_NUMA
mpol_put(p->mempolicy);
bad_fork_cleanup_threadgroup_lock: