On Thu, Jun 29, 2017 at 6:22 PM, Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote: > On Tue, Jun 27, 2017 at 07:05:27PM +0200, Pablo Neira Ayuso wrote: >> On Tue, Jun 27, 2017 at 05:58:25PM +0200, Pablo Neira Ayuso wrote: >> > On Wed, Jun 07, 2017 at 03:50:38PM +0200, Mateusz Jurczyk wrote: >> > > Verify that the length of the socket buffer is sufficient to cover the >> > > nlmsghdr structure before accessing the nlh->nlmsg_len field for further >> > > input sanitization. If the client only supplies 1-3 bytes of data in >> > > sk_buff, then nlh->nlmsg_len remains partially uninitialized and >> > > contains leftover memory from the corresponding kernel allocation. >> > > Operating on such data may result in indeterminate evaluation of the >> > > nlmsg_len < NLMSG_HDRLEN expression. >> > > >> > > The bug was discovered by a runtime instrumentation designed to detect >> > > use of uninitialized memory in the kernel. The patch prevents this and >> > > other similar tools (e.g. KMSAN) from flagging this behavior in the future. >> > >> > Applied, thanks. >> >> Wait, I keeping this back after closer look. >> >> I think we have to remove this: >> >> if (nlh->nlmsg_len < NLMSG_HDRLEN || <--- >> skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) >> return; >> >> in nfnetlink_rcv_skb_batch() >> >> now that we make this unfront check from nfnetlink_rcv(). > > BTW, I can just mangle your patch here to delete such line to speed up > things. See the mangled patch that is attached to this email. Sure, I think the condition in nfnetlink_rcv_skb_batch() can be now safely removed. Feel free to proceed with the mangled patch. Thanks. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
