From aea5e37388a080361110ab5790f57ae0af383650 Mon Sep 17 00:00:00 2001 From: Bharath SM Date: Mon, 9 Mar 2026 16:00:49 +0530 Subject: smb: client: fix in-place encryption corruption in SMB2_write() commit d78840a6a38d312dc1a51a65317bb67e46f0b929 upstream. SMB2_write() places write payload in iov[1..n] as part of rq_iov. smb3_init_transform_rq() pointer-shares rq_iov, so crypt_message() encrypts iov[1] in-place, replacing the original plaintext with ciphertext. On a replayable error, the retry sends the same iov[1] which now contains ciphertext instead of the original data, resulting in corruption. The corruption is most likely to be observed when connections are unstable, as reconnects trigger write retries that re-send the already-encrypted data. This affects SFU mknod, MF symlinks, etc. On kernels before 6.10 (prior to the netfs conversion), sync writes also used this path and were similarly affected. The async write path wasn't unaffected as it uses rq_iter which gets deep-copied. Fix by moving the write payload into rq_iter via iov_iter_kvec(), so smb3_init_transform_rq() deep-copies it before encryption. Cc: stable@vger.kernel.org #6.3+ Acked-by: Henrique Carvalho Acked-by: Shyam Prasad N Acked-by: Paulo Alcantara (Red Hat) Signed-off-by: Bharath SM Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/smb2pdu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index bf4a13acc8b8..a00bcfd08152 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -5237,7 +5237,10 @@ replay_again: memset(&rqst, 0, sizeof(struct smb_rqst)); rqst.rq_iov = iov; - rqst.rq_nvec = n_vec + 1; + /* iov[0] is the SMB header; move payload to rq_iter for encryption safety */ + rqst.rq_nvec = 1; + iov_iter_kvec(&rqst.rq_iter, ITER_SOURCE, &iov[1], n_vec, + io_parms->length); if (retries) smb2_set_replay(server, &rqst); -- cgit v1.2.3