From: Masami Hiramatsu (Google) mhiramat@kernel.org
commit dec8784c9088b131a1523f582c2194cfc8107dc0 upstream.
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@posteo.net Signed-off-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Tested-by: Daniel Müller deso@posteo.net Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20220727210136.jjgc3lpqeq42yr3m@muellerd-fedora-... Link: https://lore.kernel.org/r/165942025658.342061.12452378391879093249.stgit@dev... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/kprobes/core.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-)
--- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -814,16 +814,20 @@ set_current_kprobe(struct kprobe *p, str 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);