kernel/fs/smb, branch linux-6.6.y

cifs: some missing initializations on replay

2026-03-04T12:21:19Z

[ Upstream commit 14f66f44646333d2bfd7ece36585874fd72f8286 ] In several places in the code, we have a label to signify the start of the code where a request can be replayed if necessary. However, some of these places were missing the necessary reinitializations of certain local variables before replay. This change makes sure that these variables get initialized after the label. Cc: stable@vger.kernel.org Reported-by: Yuchan Nam Tested-by: Yuchan Nam Signed-off-by: Shyam Prasad N Signed-off-by: Steve French Signed-off-by: Sasha Levin

cifs: Fix locking usage for tcon fields

2026-03-04T12:21:16Z

[ Upstream commit 96c4af418586ee9a6aab61738644366426e05316 ] We used to use the cifs_tcp_ses_lock to protect a lot of objects that are not just the server, ses or tcon lists. We later introduced srv_lock, ses_lock and tc_lock to protect fields within the corresponding structs. This was done to provide a more granular protection and avoid unnecessary serialization. There were still a couple of uses of cifs_tcp_ses_lock to provide tcon fields. In this patch, I've replaced them with tc_lock. Cc: stable@vger.kernel.org Signed-off-by: Shyam Prasad N Signed-off-by: Steve French Signed-off-by: Sasha Levin

smb: client: prevent races in ->query_interfaces()

2026-03-04T12:20:32Z

[ Upstream commit c3c06e42e1527716c54f3ad2ced6a034b5f3a489 ] It was possible for two query interface works to be concurrently trying to update the interfaces. Prevent this by checking and updating iface_last_update under iface_lock. Signed-off-by: Henrique Carvalho Signed-off-by: Steve French Signed-off-by: Sasha Levin

smb: client: add proper locking around ses->iface_last_update

2026-03-04T12:20:32Z

[ Upstream commit e97dcac3dc0bd37e4b56aaa6874b572a3a461102 ] There is a missing ses->iface_lock in cifs_setup_session, around ses->iface_last_update. Signed-off-by: Henrique Carvalho Signed-off-by: Steve French Signed-off-by: Sasha Levin

smb: client: correct value for smbd_max_fragmented_recv_size

2026-03-04T12:19:52Z

[ Upstream commit 4a93d1ee2d0206970b6eb13fbffe07938cd95948 ] When we download a file without rdma offload or get a large directly enumeration from the server, the server might want to send up to smbd_max_fragmented_recv_size bytes, but if it is too large all our recv buffers might already be moved to the recv_io.reassembly.list and we're no longer able to grant recv credits. The maximum fragmented upper-layer payload receive size supported Assume max_payload_per_credit is smbd_max_receive_size - 24 = 1340 The maximum number would be smbd_receive_credit_max * max_payload_per_credit 1340 * 255 = 341700 (0x536C4) The minimum value from the spec is 131072 (0x20000) For now we use the logic we used in ksmbd before: (1364 * 255) / 2 = 173910 (0x2A756) Fixes: 03bee01d6215 ("CIFS: SMBD: Add SMB Direct protocol initial values and constants") Cc: Steve French Cc: Tom Talpey Cc: Long Li Cc: Namjae Jeon Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Signed-off-by: Stefan Metzmacher Signed-off-by: Steve French Signed-off-by: Sasha Levin

smb: client: fix potential UAF and double free in smb2_open_file()

2026-03-04T12:19:26Z

[ Upstream commit ebbbc4bfad4cb355d17c671223d0814ee3ef4eda ] Zero out @err_iov and @err_buftype before retrying SMB2_open() to prevent an UAF bug if @data != NULL, otherwise a double free. Fixes: e3a43633023e ("smb/client: fix memory leak in smb2_open_file()") Reported-by: David Howells Closes: https://lore.kernel.org/r/2892312.1770306653@warthog.procyon.org.uk Signed-off-by: Paulo Alcantara (Red Hat) Reviewed-by: David Howells Reviewed-by: ChenXiaoSong Cc: linux-cifs@vger.kernel.org Signed-off-by: Steve French Signed-off-by: Sasha Levin

smb: server: fix leak of active_num_conn in ksmbd_tcp_new_connection()

2026-02-16T09:17:47Z

commit 77ffbcac4e569566d0092d5f22627dfc0896b553 upstream. On kthread_run() failure in ksmbd_tcp_new_connection(), the transport is freed via free_transport(), which does not decrement active_num_conn, leaking this counter. Replace free_transport() with ksmbd_tcp_disconnect(). Fixes: 0d0d4680db22e ("ksmbd: add max connections parameter") Cc: stable@vger.kernel.org Signed-off-by: Henrique Carvalho Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

ksmbd: fix infinite loop caused by next_smb2_rcv_hdr_off reset in error paths

2026-02-16T09:17:47Z

commit 010eb01ce23b34b50531448b0da391c7f05a72af upstream. The problem occurs when a signed request fails smb2 signature verification check. In __process_request(), if check_sign_req() returns an error, set_smb2_rsp_status(work, STATUS_ACCESS_DENIED) is called. set_smb2_rsp_status() set work->next_smb2_rcv_hdr_off as zero. By resetting next_smb2_rcv_hdr_off to zero, the pointer to the next command in the chain is lost. Consequently, is_chained_smb2_message() continues to point to the same request header instead of advancing. If the header's NextCommand field is non-zero, the function returns true, causing __handle_ksmbd_work() to repeatedly process the same failed request in an infinite loop. This results in the kernel log being flooded with "bad smb2 signature" messages and high CPU usage. This patch fixes the issue by changing the return value from SERVER_HANDLER_CONTINUE to SERVER_HANDLER_ABORT. This ensures that the processing loop terminates immediately rather than attempting to continue from an invalidated offset. Reported-by: tianshuo han Cc: stable@vger.kernel.org Signed-off-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

smb: client: split cached_fid bitfields to avoid shared-byte RMW races

2026-02-16T09:17:47Z

commit ec306600d5ba7148c9dbf8f5a8f1f5c1a044a241 upstream. is_open, has_lease and on_list are stored in the same bitfield byte in struct cached_fid but are updated in different code paths that may run concurrently. Bitfield assignments generate byte read–modify–write operations (e.g. `orb $mask, addr` on x86_64), so updating one flag can restore stale values of the others. A possible interleaving is: CPU1: load old byte (has_lease=1, on_list=1) CPU2: clear both flags (store 0) CPU1: RMW store (old | IS_OPEN) -> reintroduces cleared bits To avoid this class of races, convert these flags to separate bool fields. Cc: stable@vger.kernel.org Fixes: ebe98f1447bbc ("cifs: enable caching of directories for which a lease is held") Signed-off-by: Henrique Carvalho Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

smb/client: fix memory leak in smb2_open_file()

2026-02-11T12:39:14Z

[ 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: 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 Reviewed-by: Paulo Alcantara (Red Hat) Signed-off-by: ChenXiaoSong Reviewed-by: Pali Rohár Signed-off-by: Steve French Signed-off-by: Sasha Levin