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. Thanks -- 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>
