[PATCH 6.18 117/175] smb/client: fix memory leak in smb2_open_file()

Greg Kroah-Hartman
2026-02-09T14:31:41Z

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

[ Upstream commit e3a43633023e3cacaca60d4b8972d084a2b06236 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/smb/client/smb2file.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/fs/smb/client/smb2file.c b/fs/smb/client/smb2file.c
index a7f6292388306..03f90553d8319 100644
--- a/fs/smb/client/smb2file.c
+++ b/fs/smb/client/smb2file.c
@@ -177,6 +177,7 @@ int smb2_open_file(const unsigned int xid, struct cifs_open_parms *oparms, __u32
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);
--
2.51.0