• Masami Hiramatsu's avatar
    kprobes: Fix error check when reusing optimized probes · 5e8002fb
    Masami Hiramatsu authored
    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: 's avatarMasami 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@devnote2Signed-off-by: 's avatarIngo Molnar <mingo@kernel.org>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    5e8002fb