From fb87d390de327c76b11ed544de83771118f7b0c5 Mon Sep 17 00:00:00 2001 From: Norbert Szetei Date: Fri, 2 May 2025 08:21:58 +0900 Subject: ksmbd: prevent out-of-bounds stream writes by validating *pos ksmbd_vfs_stream_write() did not validate whether the write offset (*pos) was within the bounds of the existing stream data length (v_len). If *pos was greater than or equal to v_len, this could lead to an out-of-bounds memory write. This patch adds a check to ensure *pos is less than v_len before proceeding. If the condition fails, -EINVAL is returned. Cc: stable@vger.kernel.org Signed-off-by: Norbert Szetei Acked-by: Namjae Jeon Signed-off-by: Steve French --- fs/smb/server/vfs.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/fs/smb/server/vfs.c +++ b/fs/smb/server/vfs.c @@ -443,6 +443,13 @@ static int ksmbd_vfs_stream_write(struct goto out; } + if (v_len <= *pos) { + pr_err("stream write position %lld is out of bounds (stream length: %zd)\n", + *pos, v_len); + err = -EINVAL; + goto out; + } + if (v_len < size) { wbuf = kvzalloc(size, KSMBD_DEFAULT_GFP); if (!wbuf) {