* [for-linus][PATCH 1/2] ftrace: Fix issue that direct->addr not restored in modify_ftrace_direct()
[not found] <20230406191058.652785135@goodmis.org>
@ 2023-04-06 19:10 ` Steven Rostedt
0 siblings, 0 replies; only message in thread
From: Steven Rostedt @ 2023-04-06 19:10 UTC (permalink / raw)
To: linux-kernel
Cc: Masami Hiramatsu, Mark Rutland, Andrew Morton, stable, ast,
daniel, Zheng Yejian
From: Zheng Yejian <zhengyejian1@huawei.com>
Syzkaller report a WARNING: "WARN_ON(!direct)" in modify_ftrace_direct().
Root cause is 'direct->addr' was changed from 'old_addr' to 'new_addr' but
not restored if error happened on calling ftrace_modify_direct_caller().
Then it can no longer find 'direct' by that 'old_addr'.
To fix it, restore 'direct->addr' to 'old_addr' explicitly in error path.
Link: https://lore.kernel.org/linux-trace-kernel/20230330025223.1046087-1-zhengyejian1@huawei.com
Cc: stable@vger.kernel.org
Cc: <mhiramat@kernel.org>
Cc: <mark.rutland@arm.com>
Cc: <ast@kernel.org>
Cc: <daniel@iogearbox.net>
Fixes: 8a141dd7f706 ("ftrace: Fix modify_ftrace_direct.")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/ftrace.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0feea145bb29..c67bcc89a771 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5667,12 +5667,15 @@ int modify_ftrace_direct(unsigned long ip,
ret = 0;
}
- if (unlikely(ret && new_direct)) {
- direct->count++;
- list_del_rcu(&new_direct->next);
- synchronize_rcu_tasks();
- kfree(new_direct);
- ftrace_direct_func_count--;
+ if (ret) {
+ direct->addr = old_addr;
+ if (unlikely(new_direct)) {
+ direct->count++;
+ list_del_rcu(&new_direct->next);
+ synchronize_rcu_tasks();
+ kfree(new_direct);
+ ftrace_direct_func_count--;
+ }
}
out_unlock:
--
2.39.2
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2023-04-06 19:10 ` [for-linus][PATCH 1/2] ftrace: Fix issue that direct->addr not restored in modify_ftrace_direct() Steven Rostedt
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