kernel/linux.git/fs/smb, branch v6.6.155

ksmbd: reject repeated SMB2 NEGOTIATE requests

2026-08-23T12:20:03+00:00

[ Upstream commit cb469993b3a61a72653770856d37af616d72d05f ] Unauthenticated client can send multiple successful SMB2 NEGOTIATE requests on one connection before SESSION_SETUP. While the connection is in KSMBD_SESS_NEED_SETUP, smb2_handle_negotiate() accepts another SMB3.1.1 NEGOTIATE and overwrites conn->preauth_info with a new allocation. Only the final allocation is freed when the connection is released, leaking one object for every additional successful request. A repeated SMB2 NEGOTIATE after a dialect has been selected is a protocol violation. MS-SMB2 section 3.3.5.4 requires the server to disconnect without replying in this case. Set the connection exiting when rejecting the request, in addition to suppressing the response. Reject SMB2 NEGOTIATE unless the connection is new or is waiting for the SMB2 NEGOTIATE that follows an SMB1 multi-protocol negotiate. Serialize both SMB1 and SMB2 negotiation paths under conn->srv_mutex, since they update connection-wide dialect and negotiation state. Move the locking contract to ksmbd_smb_negotiate_common(), where the state and dialect are selected, and add ksmbd_conn_new() for consistent state access. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Reported-by: Runa Takemoto Signed-off-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ksmbd: conn lock to serialize smb2 negotiate

2026-08-23T12:20:03+00:00

[ Upstream commit fe4ed2f09b492e3507615a053814daa8fafdecb1 ] If client send parallel smb2 negotiate request on same connection, ksmbd_conn can be racy. smb2 negotiate handling that are not performance-related can be serialized with conn lock. Signed-off-by: Namjae Jeon Signed-off-by: Steve French Stable-dep-of: cb469993b3a6 ("ksmbd: reject repeated SMB2 NEGOTIATE requests") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ksmbd: validate minimum PDU size for transform requests

2026-08-23T12:20:02+00:00

[ Upstream commit cfc0b8e5080aec87700774e8568765eaa4b7b92b ] The receive path applies the minimum SMB2 PDU size check only when ProtocolId is SMB2_PROTO_NUMBER. A packet carrying SMB2_TRANSFORM_PROTO_NUM bypasses the check even when the negotiated dialect does not provide transform handling. On an SMB 2.1 connection, a short transform packet therefore reaches init_smb2_rsp_hdr(), which interprets the request as a full SMB2 header and reads beyond the request allocation. The copied fields can then be returned to the unauthenticated client. Compression transforms are converted to ordinary SMB2 messages before protocol validation. After that conversion, validate ordinary SMB2 requests against SMB2_MIN_SUPPORTED_PDU_SIZE and require encryption transform requests to contain both a transform header and an SMB2 header. This rejects truncated requests before work allocation. Fixes: 368ba06881c3 ("ksmbd: check the validation of pdu_size in ksmbd_conn_handler_loop") Cc: stable@vger.kernel.org Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-31063 Signed-off-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb/server: fix minimum SMB2 PDU size

2026-08-23T12:20:02+00:00

[ Upstream commit 4c7d8eb9a79ae5400eac19c4f6f0815bff674452 ] The minimum SMB2 PDU size should be updated to the size of `struct smb2_pdu` (that is, the size of `struct smb2_hdr` + 2). Suggested-by: David Howells Suggested-by: Namjae Jeon Signed-off-by: ChenXiaoSong Reviewed-by: David Howells Acked-by: Namjae Jeon Signed-off-by: Steve French Stable-dep-of: cfc0b8e5080a ("ksmbd: validate minimum PDU size for transform requests") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb/server: fix minimum SMB1 PDU size

2026-08-23T12:20:02+00:00

[ Upstream commit 3b9c30eb8f5aaad4a54cdfa470b74c0467cc71e8 ] Since the RFC1002 header has been removed from `struct smb_hdr`, the minimum SMB1 PDU size should be updated as well. Fixes: 83bfbd0bb902 ("cifs: Remove the RFC1002 header from smb_hdr") Suggested-by: David Howells Suggested-by: Namjae Jeon Signed-off-by: ChenXiaoSong Reviewed-by: David Howells Acked-by: Namjae Jeon Signed-off-by: Steve French Stable-dep-of: cfc0b8e5080a ("ksmbd: validate minimum PDU size for transform requests") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ksmbd: rename smb2_get_msg to smb_get_msg

2026-08-23T12:20:02+00:00

[ Upstream commit 0b444cfd8b74ebce421ccd96eac9c495e536c92e ] With the removal of the RFC1002 length field from the SMB header, smb2_get_msg is now used to get the smb1 request from the request buffer. Since this function is no longer exclusive to smb2 and now supports smb1 as well, This patch rename it to smb_get_msg to better reflect its usage. Signed-off-by: Namjae Jeon Signed-off-by: Steve French Stable-dep-of: cfc0b8e5080a ("ksmbd: validate minimum PDU size for transform requests") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb/server: rename include guard in smb_common.h

2026-08-23T12:20:02+00:00

[ Upstream commit 01ab0d1640e379f0a0d6602250b33ff2b45e9560 ] Make the include guard more descriptive to avoid conflicts with include guards that may be used in the future. Signed-off-by: ChenXiaoSong Acked-by: Namjae Jeon Signed-off-by: Steve French Stable-dep-of: cfc0b8e5080a ("ksmbd: validate minimum PDU size for transform requests") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb: move get_rfc1002_len() to common/smbglob.h

2026-08-23T12:20:02+00:00

[ Upstream commit 36c31540cf5279262bfd148d8537cd04866499f2 ] Rename get_rfc1002_length() to get_rfc1002_len(), then move duplicate definitions to common header file. Co-developed-by: ChenXiaoSong Signed-off-by: ChenXiaoSong Signed-off-by: ZhangGuoDong Acked-by: Namjae Jeon Signed-off-by: Steve French Stable-dep-of: cfc0b8e5080a ("ksmbd: validate minimum PDU size for transform requests") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb: move smb_version_values to common/smbglob.h

2026-08-23T12:20:02+00:00

[ Upstream commit 34cf191bb6a349dc88ec2c4f6355fe006ac669e0 ] Merge the struct members of the server and the client: - req_capabilities: from client - header_preamble_size: from client - cap_unicode: from client - capabilities: from server, rename to req_capabilities - max_read_size: from server - max_write_size: from server - max_trans_size: from server - max_credits: from server - create_durable_size: from server - create_durable_v2_size: from server - create_mxac_size: from server - create_disk_id_size: from server - create_posix_size: from server Then move duplicate definitions to common header file. Co-developed-by: ChenXiaoSong Signed-off-by: ChenXiaoSong Signed-off-by: ZhangGuoDong Acked-by: Namjae Jeon Signed-off-by: Steve French Stable-dep-of: cfc0b8e5080a ("ksmbd: validate minimum PDU size for transform requests") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb: client: Fix use-after-free in cifs_try_adding_channels()

2026-08-19T16:13:13+00:00

commit 4986410316b1ae0e63c6ce418e4eb196723626e7 upstream. cifs_try_adding_channels() takes a temporary reference to an interface before dropping iface_lock. If cifs_ses_add_channel() fails, it drops that reference and then increments iface->weight_fulfilled. A concurrent interface list refresh can remove the list reference while channel creation is in progress. In that case, the failure-path kref_put() releases the last reference and frees iface. Updating weight_fulfilled afterward then accesses freed memory. Increment weight_fulfilled before dropping the temporary reference, keeping iface alive for the final access. Fixes: 6aac002bcfd5 ("cifs: failure to add channel on iface should bump up weight") Cc: stable@vger.kernel.org Signed-off-by: Shuangpeng Bai Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman