Patch "ftrace: Fix issue that 'direct->addr' not restored in modify_ftrace_direct()" has been added to the 6.2-stable tree

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This is a note to let you know that I've just added the patch titled

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

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-issue-that-direct-addr-not-restored-in-modify_ftrace_direct.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 2a2d8c51defb446e8d89a83f42f8e5cd529111e9 Mon Sep 17 00:00:00 2001
From: Zheng Yejian <zhengyejian1@xxxxxxxxxx>
Date: Thu, 30 Mar 2023 10:52:23 +0800
Subject: ftrace: Fix issue that 'direct->addr' not restored in modify_ftrace_direct()

From: Zheng Yejian <zhengyejian1@xxxxxxxxxx>

commit 2a2d8c51defb446e8d89a83f42f8e5cd529111e9 upstream.

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@xxxxxxxxxx

Cc: stable@xxxxxxxxxxxxxxx
Cc: <mhiramat@xxxxxxxxxx>
Cc: <mark.rutland@xxxxxxx>
Cc: <ast@xxxxxxxxxx>
Cc: <daniel@xxxxxxxxxxxxx>
Fixes: 8a141dd7f706 ("ftrace: Fix modify_ftrace_direct.")
Signed-off-by: Zheng Yejian <zhengyejian1@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 kernel/trace/ftrace.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5568,12 +5568,15 @@ int modify_ftrace_direct(unsigned long i
 		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:


Patches currently in stable-queue which might be from zhengyejian1@xxxxxxxxxx are

queue-6.2/ftrace-fix-issue-that-direct-addr-not-restored-in-modify_ftrace_direct.patch



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