Re: [PATCH -tip v2] kprobes: Prohibit probing on BUG() and WARN() address

From: Naveen N. Rao
Date: Wed Sep 04 2019 - 05:13:38 EST

Masami Hiramatsu wrote:
Since BUG() and WARN() may use a trap (e.g. UD2 on x86) to
get the address where the BUG() has occurred, kprobes can not
do single-step out-of-line that instruction. So prohibit
probing on such address.

Without this fix, if someone put a kprobe on WARN(), the
kernel will crash with invalid opcode error instead of
outputing warning message, because kernel can not find
correct bug address.

Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Changes in v2:
- Add find_bug() stub function for !CONFIG_GENERIC_BUG
- Cast the p->addr to unsigned long.
include/linux/bug.h | 5 +++++
kernel/kprobes.c | 3 ++-
2 files changed, 7 insertions(+), 1 deletion(-)

Acked-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>

- Naveen