On Wed, Feb 27, 2019 at 06:13:19AM -0700, Jens Axboe wrote: > On 2/26/19 11:11 PM, Eric Biggers wrote: > > On Tue, Feb 26, 2019 at 10:02:04PM -0800, syzbot wrote: > >> Hello, > >> > >> syzbot found the following crash on: > >> > >> HEAD commit: 8e7f81e2ebc4 Add linux-next specific files for 20190226 > >> git tree: linux-next > >> console output: https://syzkaller.appspot.com/x/log.txt?x=10381714c00000 > >> kernel config: https://syzkaller.appspot.com/x/.config?x=2fa10211b8a4a56e > >> dashboard link: https://syzkaller.appspot.com/bug?extid=a5b71df98b247d973f8c > >> compiler: gcc (GCC) 9.0.0 20181231 (experimental) > >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14eda192c00000 > >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=164831e0c00000 > >> > >> IMPORTANT: if you fix the bug, please add the following tag to the commit: > >> Reported-by: syzbot+a5b71df98b247d973f8c@xxxxxxxxxxxxxxxxxxxxxxxxx > >> > >> page:ffffea00025c3ac0 count:0 mapcount:0 mapping:0000000000000000 index:0x0 > >> flags: 0x1fffc0000000000() > >> raw: 01fffc0000000000 ffffea00024bf988 ffffea00021dd448 0000000000000000 > >> raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 > >> page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0) > >> ------------[ cut here ]------------ > >> kernel BUG at include/linux/mm.h:579! > >> invalid opcode: 0000 [#1] PREEMPT SMP KASAN > >> CPU: 0 PID: 7779 Comm: syz-executor379 Not tainted 5.0.0-rc8-next-20190226 > >> #43 > >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > >> Google 01/01/2011 > >> RIP: 0010:put_page_testzero include/linux/mm.h:579 [inline] > >> RIP: 0010:put_page include/linux/mm.h:1025 [inline] > >> RIP: 0010:generic_pipe_buf_release+0x120/0x160 fs/pipe.c:224 > >> Code: bd ff 4c 89 e7 e8 90 43 db ff e8 bb 29 bd ff 5b 41 5c 41 5d 5d c3 e8 > >> af 29 bd ff 48 c7 c6 20 98 75 87 4c 89 e7 e8 c0 db e4 ff <0f> 0b e8 99 29 bd > >> ff 4d 8d 65 ff e9 3d ff ff ff 48 89 df e8 e8 f8 > >> RSP: 0018:ffff8880a503f920 EFLAGS: 00010293 > >> RAX: ffff88808d2ec6c0 RBX: ffffea00025c3af4 RCX: 0000000000000000 > >> RDX: 0000000000000000 RSI: ffffffff81982852 RDI: ffffea00025c3af8 > >> RBP: ffff8880a503f938 R08: 000000000000003e R09: ffffed1015d05011 > >> R10: ffffed1015d05010 R11: ffff8880ae828087 R12: ffffea00025c3ac0 > >> R13: 0000000000000000 R14: ffff88809b6e8a40 R15: ffff8880952c4000 > >> FS: 00000000016a0880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 > >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >> CR2: 0000000020f50f90 CR3: 0000000097b89000 CR4: 00000000001406f0 > >> Call Trace: > >> pipe_buf_release include/linux/pipe_fs_i.h:129 [inline] > >> iter_file_splice_write+0x7d1/0xbe0 fs/splice.c:759 > >> do_splice_from fs/splice.c:847 [inline] > >> direct_splice_actor+0x126/0x1a0 fs/splice.c:1019 > >> splice_direct_to_actor+0x369/0x970 fs/splice.c:974 > >> do_splice_direct+0x1da/0x2a0 fs/splice.c:1062 > >> do_sendfile+0x597/0xd00 fs/read_write.c:1442 > >> __do_sys_sendfile64 fs/read_write.c:1503 [inline] > >> __se_sys_sendfile64 fs/read_write.c:1489 [inline] > >> __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1489 > >> do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > >> entry_SYSCALL_64_after_hwframe+0x49/0xbe > >> RIP: 0033:0x443d29 > >> Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 > >> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff > >> 0f 83 7b d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > >> RSP: 002b:00007fffc1e47c88 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 > >> RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443d29 > >> RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000003 > >> RBP: 00000000006ce018 R08: 00000000004002e0 R09: 00000000004002e0 > >> R10: 0000000102000300 R11: 0000000000000246 R12: 0000000000401a30 > >> R13: 0000000000401ac0 R14: 0000000000000000 R15: 0000000000000000 > >> Modules linked in: > >> ---[ end trace 9daff95e0e1a45ff ]--- > >> RIP: 0010:put_page_testzero include/linux/mm.h:579 [inline] > >> RIP: 0010:put_page include/linux/mm.h:1025 [inline] > >> RIP: 0010:generic_pipe_buf_release+0x120/0x160 fs/pipe.c:224 > >> Code: bd ff 4c 89 e7 e8 90 43 db ff e8 bb 29 bd ff 5b 41 5c 41 5d 5d c3 e8 > >> af 29 bd ff 48 c7 c6 20 98 75 87 4c 89 e7 e8 c0 db e4 ff <0f> 0b e8 99 29 bd > >> ff 4d 8d 65 ff e9 3d ff ff ff 48 89 df e8 e8 f8 > >> RSP: 0018:ffff8880a503f920 EFLAGS: 00010293 > >> RAX: ffff88808d2ec6c0 RBX: ffffea00025c3af4 RCX: 0000000000000000 > >> RDX: 0000000000000000 RSI: ffffffff81982852 RDI: ffffea00025c3af8 > >> RBP: ffff8880a503f938 R08: 000000000000003e R09: ffffed1015d05011 > >> R10: ffffed1015d05010 R11: ffff8880ae828087 R12: ffffea00025c3ac0 > >> R13: 0000000000000000 R14: ffff88809b6e8a40 R15: ffff8880952c4000 > >> FS: 00000000016a0880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 > >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >> CR2: 0000000020f50f90 CR3: 0000000097b89000 CR4: 00000000001406f0 > >> > >> > >> --- > >> This bug is generated by a bot. It may contain errors. > >> See https://goo.gl/tpsmEJ for more information about syzbot. > >> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > >> > >> syzbot will keep track of this bug report. See: > >> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with > >> syzbot. > >> syzbot can test patches for this bug, for details see: > >> https://goo.gl/tpsmEJ#testing-patches > >> > > > > This is the same bug I already reported here and Jens is working on: > > https://marc.info/?l=linux-api&m=155115288114046&w=2 > > I'll mark this fixed once the fix is folded in and in linux-next. > > It should already be, I folded in the fix about 24h ago. > Yep, it's fixed in next-20190227. The fix was folded into "block: implement bio helper to add iter bvec pages to bio". Telling syzbot to invalidate this bug report: #syz invalid - Eric
