This is a note to let you know that I've just added the patch titled arm: kprobes: Allow to handle reentered kprobe on single-stepping to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: arm-kprobes-allow-to-handle-reentered-kprobe-on-single-stepping.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From f3fbd7ec62dec1528fb8044034e2885f2b257941 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Date: Tue, 14 Feb 2017 00:03:38 +0900 Subject: arm: kprobes: Allow to handle reentered kprobe on single-stepping From: Masami Hiramatsu <mhiramat@xxxxxxxxxx> commit f3fbd7ec62dec1528fb8044034e2885f2b257941 upstream. This is arm port of commit 6a5022a56ac3 ("kprobes/x86: Allow to handle reentered kprobe on single-stepping") Since the FIQ handlers can interrupt in the single stepping (or preparing the single stepping, do_debug etc.), we should consider a kprobe is hit in the NMI handler. Even in that case, the kprobe is allowed to be reentered as same as the kprobes hit in kprobe handlers (KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE). The real issue will happen when a kprobe hit while another reentered kprobe is processing (KPROBE_REENTER), because we already consumed a saved-area for the previous kprobe. Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Signed-off-by: Jon Medhurst <tixy@xxxxxxxxxx> Fixes: 24ba613c9d6c ("ARM kprobes: core code") Cc: stable@xxxxxxxxxxxxxxx #v2.6.25~v4.11 Signed-off-by: huangshaobo <huangshaobo6@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm/probes/kprobes/core.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/arch/arm/probes/kprobes/core.c +++ b/arch/arm/probes/kprobes/core.c @@ -270,6 +270,7 @@ void __kprobes kprobe_handler(struct pt_ switch (kcb->kprobe_status) { case KPROBE_HIT_ACTIVE: case KPROBE_HIT_SSDONE: + case KPROBE_HIT_SS: /* A pre- or post-handler probe got us here. */ kprobes_inc_nmissed_count(p); save_previous_kprobe(kcb); @@ -278,6 +279,11 @@ void __kprobes kprobe_handler(struct pt_ singlestep(p, regs, kcb); restore_previous_kprobe(kcb); break; + case KPROBE_REENTER: + /* A nested probe was hit in FIQ, it is a BUG */ + pr_warn("Unrecoverable kprobe detected at %p.\n", + p->addr); + /* fall through */ default: /* impossible cases */ BUG(); Patches currently in stable-queue which might be from mhiramat@xxxxxxxxxx are queue-4.9/arm-kprobes-allow-to-handle-reentered-kprobe-on-single-stepping.patch