From a26054d184763969a411e3939fe243516715ff59 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Fri, 14 Feb 2014 07:21:00 -0500 Subject: [PATCH] cifs: sanity check length of data to send before sending We had a bug discovered recently where an upper layer function (cifs_iovec_write) could pass down a smb_rqst with an invalid amount of data in it. The length of the SMB frame would be correct, but the rqst struct would cause smb_send_rqst to send nearly 4GB of data. This should never be the case. Add some sanity checking to the beginning of smb_send_rqst that ensures that the amount of data we're going to send agrees with the length in the RFC1002 header. If it doesn't, WARN() and return -EIO to the upper layers. Signed-off-by: Jeff Layton Acked-by: Sachin Prabhu Reviewed-by: Pavel Shilovsky Signed-off-by: Steve French --- fs/cifs/transport.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index b37570952846..18cd5650a5fc 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -270,6 +270,26 @@ cifs_rqst_page_to_kvec(struct smb_rqst *rqst, unsigned int idx, iov->iov_len = rqst->rq_pagesz; } +static unsigned long +rqst_len(struct smb_rqst *rqst) +{ + unsigned int i; + struct kvec *iov = rqst->rq_iov; + unsigned long buflen = 0; + + /* total up iov array first */ + for (i = 0; i < rqst->rq_nvec; i++) + buflen += iov[i].iov_len; + + /* add in the page array if there is one */ + if (rqst->rq_npages) { + buflen += rqst->rq_pagesz * (rqst->rq_npages - 1); + buflen += rqst->rq_tailsz; + } + + return buflen; +} + static int smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst) { @@ -277,6 +297,7 @@ smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst) struct kvec *iov = rqst->rq_iov; int n_vec = rqst->rq_nvec; unsigned int smb_buf_length = get_rfc1002_length(iov[0].iov_base); + unsigned long send_length; unsigned int i; size_t total_len = 0, sent; struct socket *ssocket = server->ssocket; @@ -285,6 +306,14 @@ smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst) if (ssocket == NULL) return -ENOTSOCK; + /* sanity check send length */ + send_length = rqst_len(rqst); + if (send_length != smb_buf_length + 4) { + WARN(1, "Send length mismatch(send_length=%lu smb_buf_length=%u)\n", + send_length, smb_buf_length); + return -EIO; + } + cifs_dbg(FYI, "Sending smb: smb_len=%u\n", smb_buf_length); dump_smb(iov[0].iov_base, iov[0].iov_len);