From: Masami Hiramatsu mhiramat@kernel.org
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: Masami Hiramatsu mhiramat@kernel.org Cc: Anil S Keshavamurthy anil.s.keshavamurthy@intel.com Cc: David S . Miller davem@davemloft.net Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Naveen N . Rao naveen.n.rao@linux.vnet.ibm.com Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org # v5.0+ Fixes: 819319fc9346 ("kprobes: Return error if we fail to reuse kprobe instead of BUG_ON()") Link: http://lkml.kernel.org/r/155530808559.32517.539898325433642204.stgit@devnote... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/kprobes.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
--- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -703,7 +703,6 @@ static void unoptimize_kprobe(struct kpr static int reuse_unused_kprobe(struct kprobe *ap) { struct optimized_kprobe *op; - int ret;
BUG_ON(!kprobe_unused(ap)); /* @@ -717,9 +716,8 @@ static int reuse_unused_kprobe(struct kp /* Enable the probe again */ ap->flags &= ~KPROBE_FLAG_DISABLED; /* Optimize it again (remove from op->list) */ - ret = kprobe_optready(ap); - if (ret) - return ret; + if (!kprobe_optready(ap)) + return -EINVAL;
optimize_kprobe(ap); return 0;