On Sun, Dec 17, 2017 at 5:45 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > On Sat, Dec 16, 2017 at 11:47 PM, syzbot > <bot+5e56fb40e0f2bc3f20402f782f0b3913cb959acc@xxxxxxxxxxxxxxxxxxxxxxxxx> > wrote: >> Hello, >> >> syzkaller hit the following crash on >> 6084b576dca2e898f5c101baef151f7bfdbb606d >> 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. >> >> Unfortunately, I don't have any reproducer for this bug yet. >> >> >> device gre0 entered promiscuous mode >> usercopy: kernel memory exposure attempt detected from 00000000a6830059 >> (kmalloc-1024) (1024 bytes) >> ------------[ cut here ]------------ >> kernel BUG at mm/usercopy.c:84! >> invalid opcode: 0000 [#1] SMP >> Dumping ftrace buffer: >> (ftrace buffer empty) >> Modules linked in: >> CPU: 1 PID: 28799 Comm: syz-executor4 Not tainted 4.15.0-rc3-next-20171214+ >> #67 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS >> Google 01/01/2011 >> RIP: 0010:report_usercopy mm/usercopy.c:76 [inline] >> RIP: 0010:__check_object_size+0x1e2/0x250 mm/usercopy.c:276 >> RSP: 0018:ffffc9000116fc50 EFLAGS: 00010286 >> RAX: 0000000000000063 RBX: ffffffff82e6518f RCX: ffffffff8123dede >> RDX: 0000000000004c58 RSI: ffffc900050ed000 RDI: ffff88021fd136f8 >> RBP: ffffc9000116fc88 R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000000 R12: ffff880216bb6050 >> R13: 0000000000000400 R14: 0000000000000001 R15: ffffffff82eda864 >> FS: 00007f61a06bc700(0000) GS:ffff88021fd00000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 0000000020a5afd8 CR3: 000000020f8a9000 CR4: 00000000001406e0 >> Call Trace: >> 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] >> old_dev_ioctl.isra.1+0x21d/0x9a0 net/bridge/br_ioctl.c:178 > > Uhh, this doesn't make sense, much like the other report... > > indices = kcalloc(num, sizeof(int), GFP_KERNEL); > if (indices == NULL) > return -ENOMEM; > > get_port_ifindices(br, indices, num); > if (copy_to_user((void __user *)args[1], indices, > num*sizeof(int))) > > offset is 0. size overlaps. usercopy checks in -next must be broken. I > will double-check. Start of heap object ending at 0x59 looks bogus, right? >> br_dev_ioctl+0x3f/0xa0 net/bridge/br_ioctl.c:392 >> dev_ifsioc+0x175/0x520 net/core/dev_ioctl.c:354 >> dev_ioctl+0x548/0x7a0 net/core/dev_ioctl.c:589 >> sock_ioctl+0x150/0x320 net/socket.c:998 >> vfs_ioctl fs/ioctl.c:46 [inline] >> do_vfs_ioctl+0xaf/0x840 fs/ioctl.c:686 >> SYSC_ioctl fs/ioctl.c:701 [inline] >> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 >> entry_SYSCALL_64_fastpath+0x1f/0x96 >> RIP: 0033:0x452a39 >> RSP: 002b:00007f61a06bbc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010 >> RAX: ffffffffffffffda RBX: 00007f61a06bc700 RCX: 0000000000452a39 >> RDX: 0000000020a59fd8 RSI: 00000000000089f0 RDI: 0000000000000014 >> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000 >> R13: 0000000000a6f7ff R14: 00007f61a06bc9c0 R15: 0000000000000000 >> Code: 7b e5 82 48 0f 44 da e8 8d 82 eb ff 48 8b 45 d0 4d 89 e9 4c 89 e1 4c >> 89 fa 48 89 de 48 c7 c7 a8 51 e6 82 49 89 c0 e8 76 b7 e3 ff <0f> 0b 48 c7 c0 >> 43 51 e6 82 eb a1 48 c7 c0 53 51 e6 82 eb 98 48 >> RIP: report_usercopy mm/usercopy.c:76 [inline] RSP: ffffc9000116fc50 >> RIP: __check_object_size+0x1e2/0x250 mm/usercopy.c:276 RSP: ffffc9000116fc50 >> ---[ end trace 5fadb883cda020dc ]--- >> Kernel panic - not syncing: Fatal exception >> Dumping ftrace buffer: >> (ftrace buffer empty) >> Kernel Offset: disabled >> Rebooting in 86400 seconds.. >> >> >> --- >> This bug is generated by a dumb bot. It may contain errors. >> See https://goo.gl/tpsmEJ for details. >> Direct all questions to syzkaller@xxxxxxxxxxxxxxxx. >> Please credit me with: Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx> >> >> syzbot will keep track of this bug report. >> Once a fix for this bug is merged into any tree, reply to this email with: >> #syz fix: exact-commit-title >> To mark this as a duplicate of another syzbot report, please reply with: >> #syz dup: exact-subject-of-another-report >> If it's a one-off invalid bug report, please reply with: >> #syz invalid >> Note: if the crash happens again, it will cause creation of a new bug >> report. >> Note: all commands must start from beginning of the line in the email body. > > > > -- > Kees Cook > Pixel Security > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/CAGXu5jLAvE9GaF%3DVdzR%3DwrUpquDSJkUXCidZMU-qb02%2BFDZW6g%40mail.gmail.com. > For more options, visit https://groups.google.com/d/optout. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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