From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit e7cc4865f0f31698ef2f7aac01a50e78968985b7 upstream.
While hunting for clues to a use-after-free, Oleg spotted that
perf_event_init_context() can loose an error value with the result
that fork() can succeed even though we did not fully inherit the perf
event context.
Spotted-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Cc: oleg@xxxxxxxxxx
Fixes: 889ff0150661 ("perf/core: Split context's event group list into pinned and non-pinned lists")
Link: http://lkml.kernel.org/r/20170316125823.190342547@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
kernel/events/core.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index a4a1516f3efc..0a360d3868c5 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7754,7 +7754,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
ret = inherit_task_group(event, parent, parent_ctx,
child, ctxn, &inherited_all);
if (ret)
- break;
+ goto out_unlock;
}
/*
@@ -7770,7 +7770,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
ret = inherit_task_group(event, parent, parent_ctx,
child, ctxn, &inherited_all);
if (ret)
- break;
+ goto out_unlock;
}
raw_spin_lock_irqsave(&parent_ctx->lock, flags);
@@ -7798,6 +7798,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
}
raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
+out_unlock:
mutex_unlock(&parent_ctx->mutex);
perf_unpin_context(parent_ctx);
--
2.12.2