On Tue, Nov 7, 2017 at 10:36 AM, syzbot <bot+2357afb48acb76780f3c18867ccfb7aa6fd6c4c9@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > Hello, > > syzkaller hit the following crash on > 5a3517e009e979f21977d362212b7729c5165d92 > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master > compiler: gcc (GCC) 7.1.1 20170620 > .config is attached > Raw console output is attached. > C reproducer is attached > syzkaller reproducer is attached. See https://goo.gl/kgGztJ > for information about syzkaller reproducers > > Please include the line _before_ the "cut here" (dumb, I know, but that's where warnings show up...) Found in the raw.log: [ 44.227177] unexpected usercopy without slab whitelist from SCTPv6 offset 1648 size 11 This means some part of the SCTPv6 slab was being poked into userspace without a usercopy whitelist. > check_heap_object mm/usercopy.c:222 [inline] > __check_object_size+0x22c/0x4f0 mm/usercopy.c:248 > check_object_size include/linux/thread_info.h:112 [inline] > check_copy_size include/linux/thread_info.h:143 [inline] > copy_to_user include/linux/uaccess.h:154 [inline] > sctp_getsockopt_events net/sctp/socket.c:4972 [inline] > sctp_getsockopt+0x2b90/0x70b0 net/sctp/socket.c:7012 > sock_common_getsockopt+0x95/0xd0 net/core/sock.c:2924 > SYSC_getsockopt net/socket.c:1882 [inline] > SyS_getsockopt+0x178/0x340 net/socket.c:1864 > entry_SYSCALL_64_fastpath+0x1f/0xbe Looking at the SCTPv6 slab declaration, it seems David and I missed the usercopy whitelist for the sctpv6_sock struct. I'll update the usercopy whitelist patch with: #syz fix: sctp: Define usercopy region in SCTP proto slab cache diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 5fd83974c5cc..8ac85877c0e4 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -8492,6 +8492,10 @@ struct proto sctpv6_prot = { .unhash = sctp_unhash, .get_port = sctp_get_port, .obj_size = sizeof(struct sctp6_sock), + .useroffset = offsetof(struct sctp_sock, subscribe), + .usersize = offsetof(struct sctp_sock, initmsg) - + offsetof(struct sctp_sock, subscribe) + + sizeof_field(struct sctp_sock, initmsg), .sysctl_mem = sysctl_sctp_mem, .sysctl_rmem = sysctl_sctp_rmem, .sysctl_wmem = sysctl_sctp_wmem, Thanks! -Kees -- Kees Cook Pixel Security -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
