Commit 5e8002fb authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Greg Kroah-Hartman

kprobes: Fix error check when reusing optimized probes

commit 5f843ed415581cfad4ef8fefe31c138a8346ca8a upstream.

The following commit introduced a bug in one of our error paths:

  819319fc9346 ("kprobes: Return error if we fail to reuse kprobe instead of BUG_ON()")

it missed to handle the return value of kprobe_optready() as
error-value. In reality, the kprobe_optready() returns a bool
result, so "true" case must be passed instead of 0.

This causes some errors on kprobe boot-time selftests on ARM:

 [   ] Beginning kprobe tests...
 [   ] Probe ARM code
 [   ]     kprobe
 [   ]     kretprobe
 [   ] ARM instruction simulation
 [   ]     Check decoding tables
 [   ]     Run test cases
 [   ] FAIL: test_case_handler not run
 [   ] FAIL: Test andge	r10, r11, r14, asr r7
 [   ] FAIL: Scenario 11
 [   ] FAIL: Scenario 7
 [   ] Total instruction simulation tests=1631, pass=1433 fail=198
 [   ] kprobe tests failed

This can happen if an optimized probe is unregistered and next
kprobe is registered on same address until the previous probe
is not reclaimed.

If this happens, a hidden aggregated probe may be kept in memory,
and no new kprobe can probe same address. Also, in that case
register_kprobe() will return "1" instead of minus error value,
which can mislead caller logic.
Signed-off-by: default avatarMasami Hiramatsu <>
Cc: Anil S Keshavamurthy <>
Cc: David S . Miller <>
Cc: Linus Torvalds <>
Cc: Naveen N . Rao <>
Cc: Peter Zijlstra <>
Cc: Thomas Gleixner <>
Cc: # v5.0+
Fixes: 819319fc9346 ("kprobes: Return error if we fail to reuse kprobe instead of BUG_ON()")
Link: default avatarIngo Molnar <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent 18a0a7c1
......@@ -703,7 +703,6 @@ static void unoptimize_kprobe(struct kprobe *p, bool force)
static int reuse_unused_kprobe(struct kprobe *ap)
struct optimized_kprobe *op;
int ret;
......@@ -717,9 +716,8 @@ static int reuse_unused_kprobe(struct kprobe *ap)
/* Enable the probe again */
/* Optimize it again (remove from op->list) */
ret = kprobe_optready(ap);
if (ret)
return ret;
if (!kprobe_optready(ap))
return -EINVAL;
return 0;
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