The following commit has been merged into the perf/kprobes branch of tip:

Commit-ID: bcb53209be5cb32d485507452edda19b78f31d84 Gitweb: https://git.kernel.org/tip/bcb53209be5cb32d485507452edda19b78f31d84 Author: Masami Hiramatsu mhiramat@kernel.org AuthorDate: Tue, 01 Sep 2020 00:12:07 +09:00 Committer: Ingo Molnar mingo@kernel.org CommitterDate: Mon, 14 Sep 2020 11:20:03 +02:00

kprobes: Fix to check probe enabled before disarm_kprobe_ftrace()

Commit:

0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler")

fixed one bug but the underlying bugs are not completely fixed yet.

If we run a kprobe_module.tc of ftracetest, a warning triggers:

# ./ftracetest test.d/kprobe/kprobe_module.tc === Ftrace unit tests === [1] Kprobe dynamic event - probing module ... ------------[ cut here ]------------ Failed to disarm kprobe-ftrace at trace_printk_irq_work+0x0/0x7e [trace_printk] (-2) WARNING: CPU: 7 PID: 200 at kernel/kprobes.c:1091 __disarm_kprobe_ftrace.isra.0+0x7e/0xa0

This is because the kill_kprobe() calls disarm_kprobe_ftrace() even if the given probe is not enabled. In that case, ftrace_set_filter_ip() fails because the given probe point is not registered to ftrace.

Fix to check the given (going) probe is enabled before invoking disarm_kprobe_ftrace().

Fixes: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler") Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/159888672694.1411785.5987998076694782591.stgit@dev... --- kernel/kprobes.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 732a701..3b61ae8 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -2235,9 +2235,10 @@ static void kill_kprobe(struct kprobe *p)

/* * The module is going away. We should disarm the kprobe which - * is using ftrace. + * is using ftrace, because ftrace framework is still available at + * MODULE_STATE_GOING notification. */ - if (kprobe_ftrace(p)) + if (kprobe_ftrace(p) && !kprobe_disabled(p) && !kprobes_all_disarmed) disarm_kprobe_ftrace(p); }