From mboxrd@z Thu Jan 1 00:00:00 1970 From: "santosh.shilimkar-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org" Subject: Re: [PATCH net] RDS: Check cmsg_len before dereferencing CMSG_DATA Date: Thu, 21 Dec 2017 22:58:35 -0800 Message-ID: References: <1513916224-9445-1-git-send-email-avinash.repaka@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit To: Avinash Repaka , "David S. Miller" , netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, rds-devel-N0ozoZBvEnrZJqsBc5GL+g@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Return-path: In-Reply-To: <1513916224-9445-1-git-send-email-avinash.repaka-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> Content-Language: en-US Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org On 12/21/17 8:17 PM, Avinash Repaka wrote: > RDS currently doesn't check if the length of the control message is > large enough to hold the required data, before dereferencing the control > message data. This results in following crash: > > BUG: KASAN: stack-out-of-bounds in rds_rdma_bytes net/rds/send.c:1013 > [inline] > BUG: KASAN: stack-out-of-bounds in rds_sendmsg+0x1f02/0x1f90 > net/rds/send.c:1066 > Read of size 8 at addr ffff8801c928fb70 by task syzkaller455006/3157 > > CPU: 0 PID: 3157 Comm: syzkaller455006 Not tainted 4.15.0-rc3+ #161 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:17 [inline] > dump_stack+0x194/0x257 lib/dump_stack.c:53 > print_address_description+0x73/0x250 mm/kasan/report.c:252 > kasan_report_error mm/kasan/report.c:351 [inline] > kasan_report+0x25b/0x340 mm/kasan/report.c:409 > __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430 > rds_rdma_bytes net/rds/send.c:1013 [inline] > rds_sendmsg+0x1f02/0x1f90 net/rds/send.c:1066 > sock_sendmsg_nosec net/socket.c:628 [inline] > sock_sendmsg+0xca/0x110 net/socket.c:638 > ___sys_sendmsg+0x320/0x8b0 net/socket.c:2018 > __sys_sendmmsg+0x1ee/0x620 net/socket.c:2108 > SYSC_sendmmsg net/socket.c:2139 [inline] > SyS_sendmmsg+0x35/0x60 net/socket.c:2134 > entry_SYSCALL_64_fastpath+0x1f/0x96 > RIP: 0033:0x43fe49 > RSP: 002b:00007fffbe244ad8 EFLAGS: 00000217 ORIG_RAX: 0000000000000133 > RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fe49 > RDX: 0000000000000001 RSI: 000000002020c000 RDI: 0000000000000003 > RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000217 R12: 00000000004017b0 > R13: 0000000000401840 R14: 0000000000000000 R15: 0000000000000000 > > To fix this, we verify that the cmsg_len is large enough to hold the > data to be read, before proceeding further. > > Reported-by: syzbot > Signed-off-by: Avinash Repaka > --- Thanks !! Acked-by: Santosh Shilimkar -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html