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| author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2014-05-08 13:47:49 +0200 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2014-05-08 15:10:56 +0200 |
| commit | 8058bd0faad860e75547cc5cb5d4ade016247a79 (patch) | |
| tree | 71172e9ae00c358e23e93c451f0b7dc45d98f436 /kernel/tracepoint.c | |
| parent | trace: module: Maintain a valid user count (diff) | |
| download | linux-8058bd0faad860e75547cc5cb5d4ade016247a79.tar.xz linux-8058bd0faad860e75547cc5cb5d4ade016247a79.zip | |
tracepoint: Fix use of tracepoint funcs after rcu free
Commit de7b2973903c "tracepoint: Use struct pointer instead of name hash
for reg/unreg tracepoints" introduces a use after free by calling
release_probes on the old struct tracepoint array before the newly
allocated array is published with rcu_assign_pointer. There is a race
window where tracepoints (RCU readers) can perform a
"use-after-grace-period-after-free", which shows up as a GPF in
stress-tests.
Link: http://lkml.kernel.org/r/53698021.5020108@oracle.com
Link: http://lkml.kernel.org/p/1399549669-25465-1-git-send-email-mathieu.desnoyers@efficios.com
Reported-by: Sasha Levin <sasha.levin@oracle.com>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Dave Jones <davej@redhat.com>
Fixes: de7b2973903c "tracepoint: Use struct pointer instead of name hash for reg/unreg tracepoints"
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/tracepoint.c')
| -rw-r--r-- | kernel/tracepoint.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index ac5b23cf7212..6620e5837ce2 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -188,7 +188,6 @@ static int tracepoint_add_func(struct tracepoint *tp, WARN_ON_ONCE(1); return PTR_ERR(old); } - release_probes(old); /* * rcu_assign_pointer has a smp_wmb() which makes sure that the new @@ -200,6 +199,7 @@ static int tracepoint_add_func(struct tracepoint *tp, rcu_assign_pointer(tp->funcs, tp_funcs); if (!static_key_enabled(&tp->key)) static_key_slow_inc(&tp->key); + release_probes(old); return 0; } @@ -221,7 +221,6 @@ static int tracepoint_remove_func(struct tracepoint *tp, WARN_ON_ONCE(1); return PTR_ERR(old); } - release_probes(old); if (!tp_funcs) { /* Removed last function */ @@ -232,6 +231,7 @@ static int tracepoint_remove_func(struct tracepoint *tp, static_key_slow_dec(&tp->key); } rcu_assign_pointer(tp->funcs, tp_funcs); + release_probes(old); return 0; } |