Patch "fail_function: Remove a redundant mutex unlock" has been added to the 5.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    fail_function: Remove a redundant mutex unlock

to the 5.9-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:
     fail_function-remove-a-redundant-mutex-unlock.patch
and it can be found in the queue-5.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit aa9f02869d4b43ff33f51d7e65da20cdfa028eb4
Author: Luo Meng <luomeng12@xxxxxxxxxx>
Date:   Wed Nov 18 22:49:31 2020 +0900

    fail_function: Remove a redundant mutex unlock
    
    [ Upstream commit 2801a5da5b25b7af9dd2addd19b2315c02d17b64 ]
    
    Fix a mutex_unlock() issue where before copy_from_user() is
    not called mutex_locked.
    
    Fixes: 4b1a29a7f542 ("error-injection: Support fault injection framework")
    Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
    Signed-off-by: Luo Meng <luomeng12@xxxxxxxxxx>
    Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
    Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
    Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
    Link: https://lore.kernel.org/bpf/160570737118.263807.8358435412898356284.stgit@devnote2
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/fail_function.c b/kernel/fail_function.c
index 63b349168da72..b0b1ad93fa957 100644
--- a/kernel/fail_function.c
+++ b/kernel/fail_function.c
@@ -253,7 +253,7 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
 
 	if (copy_from_user(buf, buffer, count)) {
 		ret = -EFAULT;
-		goto out;
+		goto out_free;
 	}
 	buf[count] = '\0';
 	sym = strstrip(buf);
@@ -307,8 +307,9 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
 		ret = count;
 	}
 out:
-	kfree(buf);
 	mutex_unlock(&fei_lock);
+out_free:
+	kfree(buf);
 	return ret;
 }