Patch "kprobes: Do not use local variable when creating debugfs file" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    kprobes: Do not use local variable when creating debugfs file

to the 5.4-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:
     kprobes-do-not-use-local-variable-when-creating-debu.patch
and it can be found in the queue-5.4 subdirectory.

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



commit 329aee3c0115d32e36b23a2bd048a069aa490069
Author: Punit Agrawal <punitagrawal@xxxxxxxxx>
Date:   Tue Sep 14 23:38:37 2021 +0900

    kprobes: Do not use local variable when creating debugfs file
    
    [ Upstream commit 8f7262cd66699a4b02eb7549b35c81b2116aad95 ]
    
    debugfs_create_file() takes a pointer argument that can be used during
    file operation callbacks (accessible via i_private in the inode
    structure). An obvious requirement is for the pointer to refer to
    valid memory when used.
    
    When creating the debugfs file to dynamically enable / disable
    kprobes, a pointer to local variable is passed to
    debugfs_create_file(); which will go out of scope when the init
    function returns. The reason this hasn't triggered random memory
    corruption is because the pointer is not accessed during the debugfs
    file callbacks.
    
    Since the enabled state is managed by the kprobes_all_disabled global
    variable, the local variable is not needed. Fix the incorrect (and
    unnecessary) usage of local variable during debugfs_file_create() by
    passing NULL instead.
    
    Link: https://lkml.kernel.org/r/163163031686.489837.4476867635937014973.stgit@devnote2
    
    Fixes: bf8f6e5b3e51 ("Kprobes: The ON/OFF knob thru debugfs")
    Signed-off-by: Punit Agrawal <punitagrawal@xxxxxxxxx>
    Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
    Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
    Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index a7812c115e487..1668439b269d3 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2712,14 +2712,13 @@ static const struct file_operations fops_kp = {
 static int __init debugfs_kprobe_init(void)
 {
 	struct dentry *dir;
-	unsigned int value = 1;
 
 	dir = debugfs_create_dir("kprobes", NULL);
 
 	debugfs_create_file("list", 0400, dir, NULL,
 			    &debugfs_kprobes_operations);
 
-	debugfs_create_file("enabled", 0600, dir, &value, &fops_kp);
+	debugfs_create_file("enabled", 0600, dir, NULL, &fops_kp);
 
 	debugfs_create_file("blacklist", 0400, dir, NULL,
 			    &debugfs_kprobe_blacklist_ops);