kprobes: Fix error check when reusing optimized probes
The following commit introduced a bug in one of our error paths:819319fc93
("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:819319fc93
("kprobes: Return error if we fail to reuse kprobe instead of BUG_ON()") Link: http://lkml.kernel.org/r/155530808559.32517.539898325433642204.stgit@devnote2 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -709,7 +709,6 @@ static void unoptimize_kprobe(struct kprobe *p, bool force)
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static int reuse_unused_kprobe(struct kprobe *ap)
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{
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struct optimized_kprobe *op;
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int ret;
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/*
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* Unused kprobe MUST be on the way of delayed unoptimizing (means
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@ -720,9 +719,8 @@ static int reuse_unused_kprobe(struct kprobe *ap)
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/* Enable the probe again */
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ap->flags &= ~KPROBE_FLAG_DISABLED;
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/* Optimize it again (remove from op->list) */
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ret = kprobe_optready(ap);
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if (ret)
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return ret;
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if (!kprobe_optready(ap))
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return -EINVAL;
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optimize_kprobe(ap);
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return 0;
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