On Tue, Dec 19, 2017 at 12:49 AM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > 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? No, that's a hashed address. %p doesn't report real addresses any more. -Kees > > >>> 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. -- Kees Cook Pixel Security -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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