This is a note to let you know that I've just added the patch titled
x86/kprobes: Update kcb status flag after singlestepping
to the 5.19-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:
x86-kprobes-update-kcb-status-flag-after-singlestepp.patch
and it can be found in the queue-5.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d71f841a854f95581d4ab63274cd768d8381a44c
Author: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Date: Tue Aug 2 15:04:16 2022 +0900
x86/kprobes: Update kcb status flag after singlestepping
[ Upstream commit dec8784c9088b131a1523f582c2194cfc8107dc0 ]
Fix kprobes to update kcb (kprobes control block) status flag to
KPROBE_HIT_SSDONE even if the kp->post_handler is not set.
This bug may cause a kernel panic if another INT3 user runs right
after kprobes because kprobe_int3_handler() misunderstands the
INT3 is kprobe's single stepping INT3.
Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Reported-by: Daniel Müller <deso@xxxxxxxxxx>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Tested-by: Daniel Müller <deso@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/all/20220727210136.jjgc3lpqeq42yr3m@muellerd-fedora-PC2BDTX9
Link: https://lore.kernel.org/r/165942025658.342061.12452378391879093249.stgit@devnote2
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 7c4ab8870da4..74167dc5f55e 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -814,16 +814,20 @@ set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
static void kprobe_post_process(struct kprobe *cur, struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
- if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
- kcb->kprobe_status = KPROBE_HIT_SSDONE;
- cur->post_handler(cur, regs, 0);
- }
-
/* Restore back the original saved kprobes variables and continue. */
- if (kcb->kprobe_status == KPROBE_REENTER)
+ if (kcb->kprobe_status == KPROBE_REENTER) {
+ /* This will restore both kcb and current_kprobe */
restore_previous_kprobe(kcb);
- else
+ } else {
+ /*
+ * Always update the kcb status because
+ * reset_curent_kprobe() doesn't update kcb.
+ */
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ if (cur->post_handler)
+ cur->post_handler(cur, regs, 0);
reset_current_kprobe();
+ }
}
NOKPROBE_SYMBOL(kprobe_post_process);
