On Wed, Nov 8, 2017 at 8:02 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?) Doh! That's just me trying to handle 200 bugs at the same time. Sorry. -- 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>
