From: ChenXiaoSong <chenxiaosong@kylinos.cn>
Date: Mon, 2 Feb 2026 08:24:07 +0000 (+0000)
Subject: smb/client: fix memory leak in smb2_open_file()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e3a43633023e3cacaca60d4b8972d084a2b06236;p=thirdparty%2Flinux.git

smb/client: fix memory leak in smb2_open_file()

Reproducer:

  1. server: directories are exported read-only
  2. client: mount -t cifs //${server_ip}/export /mnt
  3. client: dd if=/dev/zero of=/mnt/file bs=512 count=1000 oflag=direct
  4. client: umount /mnt
  5. client: sleep 1
  6. client: modprobe -r cifs

The error message is as follows:

  =============================================================================
  BUG cifs_small_rq (Not tainted): Objects remaining on __kmem_cache_shutdown()
  -----------------------------------------------------------------------------

  Object 0x00000000d47521be @offset=14336
  ...
  WARNING: mm/slub.c:1251 at __kmem_cache_shutdown+0x34e/0x440, CPU#0: modprobe/1577
  ...
  Call Trace:
   <TASK>
   kmem_cache_destroy+0x94/0x190
   cifs_destroy_request_bufs+0x3e/0x50 [cifs]
   cleanup_module+0x4e/0x540 [cifs]
   __se_sys_delete_module+0x278/0x400
   __x64_sys_delete_module+0x5f/0x70
   x64_sys_call+0x2299/0x2ff0
   do_syscall_64+0x89/0x350
   entry_SYSCALL_64_after_hwframe+0x76/0x7e
  ...
  kmem_cache_destroy cifs_small_rq: Slab cache still has objects when called from cifs_destroy_request_bufs+0x3e/0x50 [cifs]
  WARNING: mm/slab_common.c:532 at kmem_cache_destroy+0x16b/0x190, CPU#0: modprobe/1577

Link: https://lore.kernel.org/linux-cifs/9751f02d-d1df-4265-a7d6-b19761b21834@linux.dev/T/#mf14808c144448b715f711ce5f0477a071f08eaf6
Fixes: e255612b5ed9 ("cifs: Add fallback for SMB2 CREATE without FILE_READ_ATTRIBUTES")
Reported-by: Paulo Alcantara <pc@manguebit.org>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Reviewed-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
---

diff --git a/fs/smb/client/smb2file.c b/fs/smb/client/smb2file.c
index 7f11ae6bb785..2dd08388ea87 100644
--- a/fs/smb/client/smb2file.c
+++ b/fs/smb/client/smb2file.c
@@ -178,6 +178,7 @@ int smb2_open_file(const unsigned int xid, struct cifs_open_parms *oparms,
 	rc = SMB2_open(xid, oparms, smb2_path, &smb2_oplock, smb2_data, NULL, &err_iov,
 		       &err_buftype);
 	if (rc == -EACCES && retry_without_read_attributes) {
+		free_rsp_buf(err_buftype, err_iov.iov_base);
 		oparms->desired_access &= ~FILE_READ_ATTRIBUTES;
 		rc = SMB2_open(xid, oparms, smb2_path, &smb2_oplock, smb2_data, NULL, &err_iov,
 			       &err_buftype);