This is a note to let you know that I've just added the patch titled
RDS: Check cmsg_len before dereferencing CMSG_DATA
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: rds-check-cmsg_len-before-dereferencing-cmsg_data.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Sun Dec 31 11:13:15 CET 2017
From: Avinash Repaka avinash.repaka@oracle.com Date: Thu, 21 Dec 2017 20:17:04 -0800 Subject: RDS: Check cmsg_len before dereferencing CMSG_DATA
From: Avinash Repaka avinash.repaka@oracle.com
[ Upstream commit 14e138a86f6347c6199f610576d2e11c03bec5f0 ]
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 syzkaller-bugs@googlegroups.com Signed-off-by: Avinash Repaka avinash.repaka@oracle.com Acked-by: Santosh Shilimkar santosh.shilimkar@oracle.com Reviewed-by: Yuval Shaia yuval.shaia@oracle.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/rds/send.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/net/rds/send.c +++ b/net/rds/send.c @@ -1006,6 +1006,9 @@ static int rds_rdma_bytes(struct msghdr continue;
if (cmsg->cmsg_type == RDS_CMSG_RDMA_ARGS) { + if (cmsg->cmsg_len < + CMSG_LEN(sizeof(struct rds_rdma_args))) + return -EINVAL; args = CMSG_DATA(cmsg); *rdma_bytes += args->remote_vec.bytes; }
Patches currently in stable-queue which might be from avinash.repaka@oracle.com are
queue-4.9/rds-check-cmsg_len-before-dereferencing-cmsg_data.patch