From: Chen Zhongjin Date: Thu, 9 Mar 2023 08:02:30 +0000 (+0800) Subject: ftrace: Fix invalid address access in lookup_rec() when index is 0 X-Git-Tag: baikal/mips/sdk6.1~35 X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=c89ee157ae7e450397d0a26f10efba64a534821e;p=kernel.git ftrace: Fix invalid address access in lookup_rec() when index is 0 commit 203a18d34f8241b66d6133db37251fa116155819 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@huawei.com Cc: stable@vger.kernel.org Fixes: a1fa044f2b61 ("ftrace: Speed up search by skipping pages by address") Suggested-by: Steven Rostedt (Google) Signed-off-by: Chen Zhongjin Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 6f726ea0fde01..59062fedeaf7c 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1537,7 +1537,8 @@ static struct dyn_ftrace *lookup_rec(unsigned long start, unsigned long end) 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,