The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x e1868ba37fd27c6a68e31565402b154beaa65df0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025092135-estate-gander-564d@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e1868ba37fd27c6a68e31565402b154beaa65df0 Mon Sep 17 00:00:00 2001 From: Stefan Metzmacher metze@samba.org Date: Thu, 11 Sep 2025 10:05:23 +0900 Subject: [PATCH] ksmbd: smbdirect: verify remaining_data_length respects max_fragmented_recv_size

This is inspired by the check for data_offset + data_length.

Cc: Steve French smfrench@gmail.com Cc: Tom Talpey tom@talpey.com Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Cc: stable@vger.kernel.org Fixes: 2ea086e35c3d ("ksmbd: add buffer validation for smb direct") Acked-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Stefan Metzmacher metze@samba.org Signed-off-by: Steve French stfrench@microsoft.com

diff --git a/fs/smb/server/transport_rdma.c b/fs/smb/server/transport_rdma.c index d52f37578276..6550bd9f002c 100644 --- a/fs/smb/server/transport_rdma.c +++ b/fs/smb/server/transport_rdma.c @@ -554,7 +554,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc) case SMB_DIRECT_MSG_DATA_TRANSFER: { struct smb_direct_data_transfer *data_transfer = (struct smb_direct_data_transfer *)recvmsg->packet; - unsigned int data_offset, data_length; + u32 remaining_data_length, data_offset, data_length; int avail_recvmsg_count, receive_credits;

if (wc->byte_len < @@ -564,6 +564,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc) return; }

+ remaining_data_length = le32_to_cpu(data_transfer->remaining_data_length); data_length = le32_to_cpu(data_transfer->data_length); data_offset = le32_to_cpu(data_transfer->data_offset); if (wc->byte_len < data_offset || @@ -572,6 +573,14 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc) smb_direct_disconnect_rdma_connection(t); return; } + if (remaining_data_length > t->max_fragmented_recv_size || + data_length > t->max_fragmented_recv_size || + (u64)remaining_data_length + (u64)data_length > + (u64)t->max_fragmented_recv_size) { + put_recvmsg(t, recvmsg); + smb_direct_disconnect_rdma_connection(t); + return; + }

if (data_length) { if (t->full_packet_received)