kernel/linux.git/fs/smb/server/server.c, branch v6.19.11

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

2026-02-16T09:13:28+00:00

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

ksmbd: rename smb2_get_msg to smb_get_msg

2025-12-22T01:20:46+00:00

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

ksmbd: Fix to handle removal of rfc1002 header from smb_hdr

2025-12-22T01:20:46+00:00

The commit that removed the RFC1002 header from struct smb_hdr didn't also fix the places in ksmbd that use it in order to provide graceful rejection of SMB1 protocol requests. Fixes: 83bfbd0bb902 ("cifs: Remove the RFC1002 header from smb_hdr") Reported-by: Namjae Jeon Link: https://lore.kernel.org/r/CAKYAXd9Ju4MFkkH5Jxfi1mO0AWEr=R35M3vQ_Xa7Yw34JoNZ0A@mail.gmail.com/ Cc: ChenXiaoSong Signed-off-by: David Howells Signed-off-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: Use HMAC-MD5 library for NTLMv2

2025-12-01T03:11:43+00:00

For the HMAC-MD5 computations in NTLMv2, use the HMAC-MD5 library instead of a "hmac(md5)" crypto_shash. This is simpler and faster. With the library there's no need to allocate memory, no need to handle errors, and the HMAC-MD5 code is accessed directly without inefficient indirect calls and other unnecessary API overhead. To preserve the existing behavior of NTLMv2 support being disabled when the kernel is booted with "fips=1", make ksmbd_auth_ntlmv2() check fips_enabled itself. Previously it relied on the error from crypto_alloc_shash("hmac(md5)") being bubbled up. I don't know for sure that this is actually needed, but this preserves the existing behavior. Signed-off-by: Eric Biggers Acked-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: Use HMAC-SHA256 library for message signing and key generation

2025-12-01T03:11:43+00:00

Convert ksmbd_sign_smb2_pdu() and generate_key() to use the HMAC-SHA256 library instead of a "hmac(sha256)" crypto_shash. This is simpler and faster. With the library there's no need to allocate memory, no need to handle errors, and the HMAC-SHA256 code is accessed directly without inefficient indirect calls and other unnecessary API overhead. Signed-off-by: Eric Biggers Acked-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: Use SHA-512 library for SMB3.1.1 preauth hash

2025-12-01T03:11:42+00:00

Convert ksmbd_gen_preauth_integrity_hash() to use the SHA-512 library instead of a "sha512" crypto_shash. This is simpler and faster. With the library there's no need to allocate memory, no need to handle errors, and the SHA-512 code is accessed directly without inefficient indirect calls and other unnecessary API overhead. Signed-off-by: Eric Biggers Acked-by: Namjae Jeon Signed-off-by: Steve French

smb: server: add a pr_info() when the server starts running

2025-09-28T23:29:52+00:00

We already have a message like: ksmbd: kill command received when the server stops running. This makes it easier for debugging in order to match any possible warnings/errors in dmesg with restarted server. Cc: Namjae Jeon Cc: Steve French Cc: Tom Talpey Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Signed-off-by: Stefan Metzmacher Acked-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: remove unnecessary softdep on crc32

2025-05-26T03:54:50+00:00

ksmbd accesses crc32 using normal function calls (as opposed to e.g. the generic crypto infrastructure's name-based algorithm resolution), so there is no need to declare a module softdep. Signed-off-by: Eric Biggers Acked-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: prevent connection release during oplock break notification

2025-03-10T17:54:32+00:00

ksmbd_work could be freed when after connection release. Increment r_count of ksmbd_conn to indicate that requests are not finished yet and to not release the connection. Cc: stable@vger.kernel.org Reported-by: Norbert Szetei Tested-by: Norbert Szetei Signed-off-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: fix broken transfers when exceeding max simultaneous operations

2024-12-16T04:20:03+00:00

Since commit 0a77d947f599 ("ksmbd: check outstanding simultaneous SMB operations"), ksmbd enforces a maximum number of simultaneous operations for a connection. The problem is that reaching the limit causes ksmbd to close the socket, and the client has no indication that it should have slowed down. This behaviour can be reproduced by setting "smb2 max credits = 128" (or lower), and transferring a large file (25GB). smbclient fails as below: $ smbclient //192.168.1.254/testshare -U user%pass smb: \> put file.bin cli_push returned NT_STATUS_USER_SESSION_DELETED putting file file.bin as \file.bin smb2cli_req_compound_submit: Insufficient credits. 0 available, 1 needed NT_STATUS_INTERNAL_ERROR closing remote file \file.bin smb: \> smb2cli_req_compound_submit: Insufficient credits. 0 available, 1 needed Windows clients fail with 0x8007003b (with smaller files even). Fix this by delaying reading from the socket until there's room to allocate a request. This effectively applies backpressure on the client, so the transfer completes, albeit at a slower rate. Fixes: 0a77d947f599 ("ksmbd: check outstanding simultaneous SMB operations") Signed-off-by: Marios Makassikis Signed-off-by: Namjae Jeon Signed-off-by: Steve French