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.
Cc: [email protected]
Fixes: 8a141dd7f706 ("ftrace: Fix modify_ftrace_direct.")
Signed-off-by: Zheng Yejian <[email protected]>
---
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:
--
2.25.1