diff options
| author | Masami Hiramatsu <mhiramat@kernel.org> | 2019-02-24 01:50:49 +0900 |
|---|---|---|
| committer | Sasha Levin <sashal@kernel.org> | 2020-06-29 20:07:56 -0400 |
| commit | 7f0e8bc7e71c1b42e81a0fcd52675bb039b4ac82 (patch) | |
| tree | e5c68a93b35ae7bc00c6cc6cb83269875bfd7fb7 /arch/x86 | |
| parent | 190d22176f8d3790533e5aae85b9937df3ac61c0 (diff) | |
x86/kprobes: Avoid kretprobe recursion bug
[ Upstream commit b191fa96ea6dc00d331dcc28c1f7db5e075693a0 ]
Avoid kretprobe recursion loop bg by setting a dummy
kprobes to current_kprobe per-CPU variable.
This bug has been introduced with the asm-coded trampoline
code, since previously it used another kprobe for hooking
the function return placeholder (which only has a nop) and
trampoline handler was called from that kprobe.
This revives the old lost kprobe again.
With this fix, we don't see deadlock anymore.
And you can see that all inner-called kretprobe are skipped.
event_1 235 0
event_2 19375 19612
The 1st column is recorded count and the 2nd is missed count.
Above shows (event_1 rec) + (event_2 rec) ~= (event_2 missed)
(some difference are here because the counter is racy)
Reported-by: Andrea Righi <righi.andrea@gmail.com>
Tested-by: Andrea Righi <righi.andrea@gmail.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: c9becf58d935 ("[PATCH] kretprobe: kretprobe-booster")
Link: http://lkml.kernel.org/r/155094064889.6137.972160690963039.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 7c48aa03fe77..7d2e2e40bbba 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -736,11 +736,16 @@ static void __used kretprobe_trampoline_holder(void) NOKPROBE_SYMBOL(kretprobe_trampoline_holder); NOKPROBE_SYMBOL(kretprobe_trampoline); +static struct kprobe kretprobe_kprobe = { + .addr = (void *)kretprobe_trampoline, +}; + /* * Called from kretprobe_trampoline */ __visible __used void *trampoline_handler(struct pt_regs *regs) { + struct kprobe_ctlblk *kcb; struct kretprobe_instance *ri = NULL; struct hlist_head *head, empty_rp; struct hlist_node *tmp; @@ -750,6 +755,17 @@ __visible __used void *trampoline_handler(struct pt_regs *regs) void *frame_pointer; bool skipped = false; + preempt_disable(); + + /* + * Set a dummy kprobe for avoiding kretprobe recursion. + * Since kretprobe never run in kprobe handler, kprobe must not + * be running at this point. + */ + kcb = get_kprobe_ctlblk(); + __this_cpu_write(current_kprobe, &kretprobe_kprobe); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + INIT_HLIST_HEAD(&empty_rp); kretprobe_hash_lock(current, &head, &flags); /* fixup registers */ @@ -825,10 +841,9 @@ __visible __used void *trampoline_handler(struct pt_regs *regs) orig_ret_address = (unsigned long)ri->ret_addr; if (ri->rp && ri->rp->handler) { __this_cpu_write(current_kprobe, &ri->rp->kp); - get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; ri->ret_addr = correct_ret_addr; ri->rp->handler(ri, regs); - __this_cpu_write(current_kprobe, NULL); + __this_cpu_write(current_kprobe, &kretprobe_kprobe); } recycle_rp_inst(ri, &empty_rp); @@ -844,6 +859,9 @@ __visible __used void *trampoline_handler(struct pt_regs *regs) kretprobe_hash_unlock(current, &flags); + __this_cpu_write(current_kprobe, NULL); + preempt_enable(); + hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { hlist_del(&ri->hlist); kfree(ri); |