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 <syzkaller-bugs@xxxxxxxxxxxxxxxx> Signed-off-by: Avinash Repaka <avinash.repaka@xxxxxxxxxx> ---
Thanks !! Acked-by: Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
