The following commit has been merged into the perf/urgent branch of tip: Commit-ID: dec8784c9088b131a1523f582c2194cfc8107dc0 Gitweb: https://git.kernel.org/tip/dec8784c9088b131a1523f582c2194cfc8107dc0 Author: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> AuthorDate: Tue, 02 Aug 2022 15:04:16 +09:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Tue, 02 Aug 2022 12:35:04 +02:00 x86/kprobes: Update kcb status flag after singlestepping 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 --- arch/x86/kernel/kprobes/core.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 7c4ab88..74167dc 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);
