On Tue, Dec 19, 2017 at 9:38 AM, syzbot <bot+6b58391c99a480699fd06e8bdaa57af9e771f7e4@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. > > > usercopy: kernel memory overwrite attempt detected to 00000000056dec9b > (kmalloc-1024) (983 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: 0 PID: 31345 Comm: syz-executor7 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:ffffc90000dbf9c8 EFLAGS: 00010296 > RAX: 0000000000000061 RBX: ffffffff82e57be7 RCX: ffffffff8123dede > RDX: 00000000000051be RSI: ffffc90002616000 RDI: ffff88021fc136f8 > RBP: ffffc90000dbfa00 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801fca28050 > R13: 00000000000003d7 R14: 0000000000000000 R15: ffffffff82edf8a5 > FS: 00007f506151b700(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000000000071c000 CR3: 00000001fb4ca004 CR4: 00000000001626f0 > DR0: 0000000020000000 DR1: 0000000020001000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 > Call Trace: > check_object_size include/linux/thread_info.h:112 [inline] > check_copy_size include/linux/thread_info.h:143 [inline] > copy_from_user include/linux/uaccess.h:146 [inline] > memdup_user_nul+0x48/0xe0 mm/util.c:227 > map_write+0x19d/0x920 kernel/user_namespace.c:903 > proc_projid_map_write+0x91/0xc0 kernel/user_namespace.c:1085 > __vfs_write+0x43/0x1e0 fs/read_write.c:480 > __kernel_write+0x72/0x140 fs/read_write.c:501 > write_pipe_buf+0x77/0x90 fs/splice.c:797 > splice_from_pipe_feed fs/splice.c:502 [inline] > __splice_from_pipe+0x138/0x250 fs/splice.c:626 > splice_from_pipe+0x66/0x90 fs/splice.c:661 > default_file_splice_write+0x40/0x70 fs/splice.c:809 > do_splice_from fs/splice.c:851 [inline] > direct_splice_actor+0x60/0x70 fs/splice.c:1018 > splice_direct_to_actor+0xfb/0x280 fs/splice.c:973 > do_splice_direct+0xac/0xe0 fs/splice.c:1061 > do_sendfile+0x216/0x440 fs/read_write.c:1413 > SYSC_sendfile64 fs/read_write.c:1468 [inline] > SyS_sendfile64+0x59/0xc0 fs/read_write.c:1460 > entry_SYSCALL_64_fastpath+0x1f/0x96 > RIP: 0033:0x452a09 > RSP: 002b:00007f506151ac58 EFLAGS: 00000212 ORIG_RAX: 0000000000000028 > RAX: ffffffffffffffda RBX: 00007f506151a950 RCX: 0000000000452a09 > RDX: 000000002030f000 RSI: 0000000000000013 RDI: 0000000000000014 > RBP: 00007f506151a940 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000007563 R11: 0000000000000212 R12: 00000000004b7366 > R13: 00007f506151aac8 R14: 00000000004b7371 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: ffffc90000dbf9c8 > RIP: __check_object_size+0x1e2/0x250 mm/usercopy.c:276 RSP: ffffc90000dbf9c8 > ---[ end trace dbe6ffc74bf4afa4 ]--- Bad things on kmalloc-1024 are most likely caused by an invalid free in pcrypt, it freed a pointer into a middle of a 1024 byte heap object which was undetected by KASAN (now there is a patch for this in mm tree) and later caused all kinds of bad things: https://groups.google.com/forum/#!topic/syzkaller-bugs/NKn_ivoPOpk https://patchwork.kernel.org/patch/10126761/ #syz dup: KASAN: use-after-free Read in __list_del_entry_valid (2) > --- > 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. > > -- > 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/001a113bb44676f52b0560ad62d4%40google.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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