Patch "ovl: fix null pointer dereference in ovl_permission()" has been added to the 6.1-stable tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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

    ovl: fix null pointer dereference in ovl_permission()

to the 6.1-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:
     ovl-fix-null-pointer-dereference-in-ovl_permission.patch
and it can be found in the queue-6.1 subdirectory.

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


>From 1a73f5b8f079fd42a544c1600beface50c63af7c Mon Sep 17 00:00:00 2001
From: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
Date: Tue, 16 May 2023 22:16:18 +0800
Subject: ovl: fix null pointer dereference in ovl_permission()

From: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>

commit 1a73f5b8f079fd42a544c1600beface50c63af7c upstream.

Following process:
          P1                     P2
 path_lookupat
  link_path_walk
   inode_permission
    ovl_permission
      ovl_i_path_real(inode, &realpath)
        path->dentry = ovl_i_dentry_upper(inode)
                          drop_cache
			   __dentry_kill(ovl_dentry)
		            iput(ovl_inode)
		             ovl_destroy_inode(ovl_inode)
		              dput(oi->__upperdentry)
		               dentry_kill(upperdentry)
		                dentry_unlink_inode
				 upperdentry->d_inode = NULL
      realinode = d_inode(realpath.dentry) // return NULL
      inode_permission(realinode)
       inode->i_sb  // NULL pointer dereference
, will trigger an null pointer dereference at realinode:
  [  335.664979] BUG: kernel NULL pointer dereference,
                 address: 0000000000000002
  [  335.668032] CPU: 0 PID: 2592 Comm: ls Not tainted 6.3.0
  [  335.669956] RIP: 0010:inode_permission+0x33/0x2c0
  [  335.678939] Call Trace:
  [  335.679165]  <TASK>
  [  335.679371]  ovl_permission+0xde/0x320
  [  335.679723]  inode_permission+0x15e/0x2c0
  [  335.680090]  link_path_walk+0x115/0x550
  [  335.680771]  path_lookupat.isra.0+0xb2/0x200
  [  335.681170]  filename_lookup+0xda/0x240
  [  335.681922]  vfs_statx+0xa6/0x1f0
  [  335.682233]  vfs_fstatat+0x7b/0xb0

Fetch a reproducer in [Link].

Use the helper ovl_i_path_realinode() to get realinode and then do
non-nullptr checking.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217405
Fixes: 4b7791b2e958 ("ovl: handle idmappings in ovl_permission()")
Cc: <stable@xxxxxxxxxxxxxxx> # v5.19
Signed-off-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
Suggested-by: Christian Brauner <brauner@xxxxxxxxxx>
Suggested-by: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/overlayfs/inode.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -286,8 +286,8 @@ int ovl_permission(struct user_namespace
 	int err;
 
 	/* Careful in RCU walk mode */
-	ovl_i_path_real(inode, &realpath);
-	if (!realpath.dentry) {
+	realinode = ovl_i_path_real(inode, &realpath);
+	if (!realinode) {
 		WARN_ON(!(mask & MAY_NOT_BLOCK));
 		return -ECHILD;
 	}
@@ -300,7 +300,6 @@ int ovl_permission(struct user_namespace
 	if (err)
 		return err;
 
-	realinode = d_inode(realpath.dentry);
 	old_cred = ovl_override_creds(inode->i_sb);
 	if (!upperinode &&
 	    !special_file(realinode->i_mode) && mask & MAY_WRITE) {


Patches currently in stable-queue which might be from chengzhihao1@xxxxxxxxxx are

queue-6.1/ovl-fix-null-pointer-dereference-in-ovl_permission.patch



[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux