This is a note to let you know that I've just added the patch titled
ftrace: Fix invalid address access in lookup_rec() when index is 0
to the 6.2-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:
ftrace-fix-invalid-address-access-in-lookup_rec-when-index-is-0.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ee92fa443358f4fc0017c1d0d325c27b37802504 Mon Sep 17 00:00:00 2001
From: Chen Zhongjin <chenzhongjin@xxxxxxxxxx>
Date: Thu, 9 Mar 2023 16:02:30 +0800
Subject: ftrace: Fix invalid address access in lookup_rec() when index is 0
From: Chen Zhongjin <chenzhongjin@xxxxxxxxxx>
commit ee92fa443358f4fc0017c1d0d325c27b37802504 upstream.
KASAN reported follow problem:
BUG: KASAN: use-after-free in lookup_rec
Read of size 8 at addr ffff000199270ff0 by task modprobe
CPU: 2 Comm: modprobe
Call trace:
kasan_report
__asan_load8
lookup_rec
ftrace_location
arch_check_ftrace_location
check_kprobe_address_safe
register_kprobe
When checking pg->records[pg->index - 1].ip in lookup_rec(), it can get a
pg which is newly added to ftrace_pages_start in ftrace_process_locs().
Before the first pg->index++, index is 0 and accessing pg->records[-1].ip
will cause this problem.
Don't check the ip when pg->index is 0.
Link: https://lore.kernel.org/linux-trace-kernel/20230309080230.36064-1-chenzhongjin@xxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 9644302e3315 ("ftrace: Speed up search by skipping pages by address")
Suggested-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Chen Zhongjin <chenzhongjin@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/ftrace.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1537,7 +1537,8 @@ static struct dyn_ftrace *lookup_rec(uns
key.flags = end; /* overload flags, as it is unsigned long */
for (pg = ftrace_pages_start; pg; pg = pg->next) {
- if (end < pg->records[0].ip ||
+ if (pg->index == 0 ||
+ end < pg->records[0].ip ||
start >= (pg->records[pg->index - 1].ip + MCOUNT_INSN_SIZE))
continue;
rec = bsearch(&key, pg->records, pg->index,
Patches currently in stable-queue which might be from chenzhongjin@xxxxxxxxxx are
queue-6.2/ftrace-fix-invalid-address-access-in-lookup_rec-when-index-is-0.patch
