From: Namjae Jeon Date: Sat, 4 Jul 2026 03:23:14 +0000 (+0900) Subject: ksmbd: reject undersized decompressed SMB2 requests X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=5e1b924808568e89c5cb132ecebe1824bd91af0c;p=thirdparty%2Fkernel%2Flinux.git ksmbd: reject undersized decompressed SMB2 requests ksmbd_decompress_request() bounds the decompressed size only against the maximum request size. A compression transform can therefore produce a buffer smaller than an SMB2 PDU and install it as conn->request_buf. The receive path subsequently calls ksmbd_smb_request(), which reads the protocol ID before the normal SMB2 minimum-size check. If the decompressed output is too short, that read can access beyond the request allocation. Require the decompressed output to contain at least a complete minimum SMB2 PDU before allocating and installing the replacement request buffer. Fixes: a08de24c2b85 ("ksmbd: negotiate and decode SMB2 compression") Cc: stable@vger.kernel.org Signed-off-by: Namjae Jeon Signed-off-by: Steve French --- diff --git a/fs/smb/server/compress.c b/fs/smb/server/compress.c index f8cf515b9c30..95e48fa6b448 100644 --- a/fs/smb/server/compress.c +++ b/fs/smb/server/compress.c @@ -56,7 +56,8 @@ int ksmbd_decompress_request(struct ksmbd_conn *conn) } max_allowed_pdu_size = SMB3_MAX_MSGSIZE + conn->vals->max_write_size; - if (out_size > max_allowed_pdu_size || + if (out_size < sizeof(struct smb2_pdu) || + out_size > max_allowed_pdu_size || out_size > MAX_STREAM_PROT_LEN) return -EINVAL;