On Wed, Nov 8, 2017 at 12:23 AM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > On Tue, Nov 7, 2017 at 9:35 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote: >> 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, please also follow this part once the commit reaches any of > trees (title is settled): > >> syzbot will keep track of this bug report. >> Once a fix for this bug is committed, please reply to this email with: >> #syz fix: exact-commit-title >> Note: all commands must start from beginning of the line. > > This will greatly help to keep the whole process running and report > new bugs in future. I included that in my email reply already, and the commit will be in -next shortly. (Do you prefer something else?) -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>
