Fix an inverted result check for reusing unused kprobe correctly. This has been introduced by commit 819319fc9346 ("kprobes: Return error if we fail to reuse kprobe instead of BUG_ON()"), which 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.

[ 4.563544] Beginning kprobe tests... [ 4.563648] Probe ARM code [ 4.563733] kprobe [ 4.564700] kretprobe [ 4.565538] ARM instruction simulation [ 4.565671] Check decoding tables [ 4.565883] Run test cases [ 5.070700] FAIL: test_case_handler not run [ 5.070938] FAIL: Test andge r10, r11, r14, asr r7 [ 5.071118] FAIL: Scenario 11 ... [ 74.174729] FAIL: Scenario 7 [ 74.211776] Total instruction simulation tests=1631, pass=1433 fail=198 [ 74.212168] 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 Fixes: 819319fc9346 ("kprobes: Return error if we fail to reuse kprobe instead of BUG_ON()") Cc: stable@vger.kernel.org # v5.0+ --- kernel/kprobes.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c index c83e54727131..b1ea30a5540e 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -709,7 +709,6 @@ static void unoptimize_kprobe(struct kprobe *p, bool force) static int reuse_unused_kprobe(struct kprobe *ap) { struct optimized_kprobe *op; - int ret;

/* * Unused kprobe MUST be on the way of delayed unoptimizing (means @@ -720,9 +719,8 @@ static int reuse_unused_kprobe(struct kprobe *ap) /* 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;