lkml.org 
[lkml]   [2019]   [Apr]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.4 162/168] kprobes: Fix error check when reusing optimized probes
    Date
    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@devnote2
    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
    @@ -668,7 +668,6 @@ 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));
    /*
    @@ -682,9 +681,8 @@ 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;

    \
     
     \ /
      Last update: 2019-04-24 20:01    [W:5.900 / U:0.404 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site