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ftrace: Fix issue that 'direct->addr' not restored in modify_ftrace_direct()

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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>
This commit is contained in:
Zheng Yejian 2023-03-30 10:52:23 +08:00 committed by Steven Rostedt (Google)
parent 3357c6e429
commit 2a2d8c51de
1 changed files with 9 additions and 6 deletions
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15
kernel/trace/ftrace.c
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@ -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: