From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Subject: question about map_read_chunks() Date: Mon, 20 Feb 2012 12:50:19 +0300 Message-ID: <20120220095019.GA21338@elgon.mountain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "J. Bruce Fields" , netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Tom Tucker Return-path: Content-Disposition: inline Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org I had a couple questions about some map_read_chunks(). net/sunrpc/xprtrdma/svc_rdma_recvfrom.c 150 ch_bytes = ntohl(ch->rc_target.rs_length); ^^^^^^^^ It look like this is 32 bits from the network? 151 head->arg.head[0] = rqstp->rq_arg.head[0]; 152 head->arg.tail[0] = rqstp->rq_arg.tail[0]; 153 head->arg.pages = &head->pages[head->count]; 154 head->hdr_count = head->count; /* save count of hdr pages */ 155 head->arg.page_base = 0; 156 head->arg.page_len = ch_bytes; 157 head->arg.len = rqstp->rq_arg.len + ch_bytes; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Can overflow. 158 head->arg.buflen = rqstp->rq_arg.buflen + ch_bytes; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Same. I didn't follow it through to see if an overflow matters. Does it? 159 head->count++; 160 chl_map->ch[0].start = 0; 161 while (byte_count) { 162 rpl_map->sge[sge_no].iov_base = 163 page_address(rqstp->rq_arg.pages[page_no]) + page_off; 164 sge_bytes = min_t(int, PAGE_SIZE-page_off, ch_bytes); ^^^ This is the wrong cast to use. A large ch_bytes would be counted as a negative value and get around the cap here. 165 rpl_map->sge[sge_no].iov_len = sge_bytes; regards, dan carpenter -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html