Commit ba439eb5 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Jiri Slaby

perf/core: Fix event inheritance on fork()

commit e7cc4865 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: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: oleg@redhat.com
Fixes: 889ff015 ("perf/core: Split context's event group list into pinned and non-pinned lists")
Link: http://lkml.kernel.org/r/20170316125823.190342547@infradead.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
parent 92ac2376
...@@ -7754,7 +7754,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn) ...@@ -7754,7 +7754,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
ret = inherit_task_group(event, parent, parent_ctx, ret = inherit_task_group(event, parent, parent_ctx,
child, ctxn, &inherited_all); child, ctxn, &inherited_all);
if (ret) if (ret)
break; goto out_unlock;
} }
/* /*
...@@ -7770,7 +7770,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn) ...@@ -7770,7 +7770,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
ret = inherit_task_group(event, parent, parent_ctx, ret = inherit_task_group(event, parent, parent_ctx,
child, ctxn, &inherited_all); child, ctxn, &inherited_all);
if (ret) if (ret)
break; goto out_unlock;
} }
raw_spin_lock_irqsave(&parent_ctx->lock, flags); raw_spin_lock_irqsave(&parent_ctx->lock, flags);
...@@ -7798,6 +7798,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn) ...@@ -7798,6 +7798,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
} }
raw_spin_unlock_irqrestore(&parent_ctx->lock, flags); raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
out_unlock:
mutex_unlock(&parent_ctx->mutex); mutex_unlock(&parent_ctx->mutex);
perf_unpin_context(parent_ctx); perf_unpin_context(parent_ctx);
......
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