Messages in this thread Patch in this message | | | Date | Thu, 31 Dec 2009 14:30:49 GMT | From | tip-bot for Peter Zijlstra <> | Subject | [tip:perf/urgent] perf: Fix NULL deref in inheritance code |
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Commit-ID: 05cbaa2853cdfc255fdd04e65a82bfe9208c4e52 Gitweb: http://git.kernel.org/tip/05cbaa2853cdfc255fdd04e65a82bfe9208c4e52 Author: Peter Zijlstra <a.p.zijlstra@chello.nl> AuthorDate: Wed, 30 Dec 2009 16:00:35 +0100 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Thu, 31 Dec 2009 13:11:31 +0100
perf: Fix NULL deref in inheritance code
Liming found a NULL deref when a task has a perf context but no counters when it forks.
This can occur in two cases, a race during construction where the fork hits after installing the context but before the first counter gets inserted, or more reproducably, a fork after the last counter is closed (which leaves the context around).
Reported-by: Wang Liming <liming.wang@windriver.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul Mackerras <paulus@samba.org> CC: <stable@kernel.org> LKML-Reference: <1262185684.7135.222.camel@laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- kernel/perf_event.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 03cc061..58ed1da 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -5148,7 +5148,7 @@ int perf_event_init_task(struct task_struct *child) GFP_KERNEL); if (!child_ctx) { ret = -ENOMEM; - goto exit; + break; } __perf_event_init_context(child_ctx, child); @@ -5164,7 +5164,7 @@ int perf_event_init_task(struct task_struct *child) } } - if (inherited_all) { + if (child_ctx && inherited_all) { /* * Mark the child context as a clone of the parent * context, or of whatever the parent is a clone of. @@ -5184,7 +5184,6 @@ int perf_event_init_task(struct task_struct *child) get_ctx(child_ctx->parent_ctx); } -exit: mutex_unlock(&parent_ctx->mutex); perf_unpin_context(parent_ctx);
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