On Wed, Feb 13, 2019 at 12:23:31PM -0800, Andrew Morton wrote: > On Wed, 13 Feb 2019 09:56:04 -0800 syzbot <syzbot+2cd2887ea471ed6e6995@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: c4f3ef3eb53f Add linux-next specific files for 20190213 > > git tree: linux-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=1130a124c00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=9ec67976eb2df882 > > dashboard link: https://syzkaller.appspot.com/bug?extid=2cd2887ea471ed6e6995 > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14ecdaa8c00000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12ebe178c00000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+2cd2887ea471ed6e6995@xxxxxxxxxxxxxxxxxxxxxxxxx > > It looks like a a memfd page was freed with a non-NULL ->mapping. > > Joel touched the memfd code with "mm/memfd: add an F_SEAL_FUTURE_WRITE > seal to memfd" but it would be surprising if syzbot tickled that code? > > > > BUG: Bad page state in process udevd pfn:472f0 > > name:"memfd:" > > page:ffffea00011cbc00 count:0 mapcount:0 mapping:ffff88800df2ad40 index:0xf > > shmem_aops > > flags: 0x1fffc000008000c(uptodate|dirty|swapbacked) > > raw: 01fffc000008000c ffffea0000ac4f08 ffff8880a85af890 ffff88800df2ad40 > > raw: 000000000000000f 0000000000000000 00000000ffffffff 0000000000000000 > > page dumped because: non-NULL mapping > > Modules linked in: > > CPU: 1 PID: 7586 Comm: udevd Not tainted 5.0.0-rc6-next-20190213 #34 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > Google 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:77 [inline] > > dump_stack+0x172/0x1f0 lib/dump_stack.c:113 > > bad_page.cold+0xda/0xff mm/page_alloc.c:586 > > free_pages_check_bad+0x142/0x1a0 mm/page_alloc.c:1014 > > free_pages_check mm/page_alloc.c:1023 [inline] > > free_pages_prepare mm/page_alloc.c:1113 [inline] > > free_pcp_prepare mm/page_alloc.c:1138 [inline] > > free_unref_page_prepare mm/page_alloc.c:2991 [inline] > > free_unref_page_list+0x31d/0xc40 mm/page_alloc.c:3060 > > name:"memfd:" > > release_pages+0x60d/0x1940 mm/swap.c:791 > > pagevec_lru_move_fn+0x218/0x2a0 mm/swap.c:213 > > __pagevec_lru_add mm/swap.c:917 [inline] > > lru_add_drain_cpu+0x2f7/0x520 mm/swap.c:581 > > lru_add_drain+0x20/0x60 mm/swap.c:652 > > exit_mmap+0x290/0x530 mm/mmap.c:3134 > > __mmput kernel/fork.c:1047 [inline] > > mmput+0x15f/0x4c0 kernel/fork.c:1068 > > exec_mmap fs/exec.c:1046 [inline] > > flush_old_exec+0x8d9/0x1c20 fs/exec.c:1279 > > load_elf_binary+0x9bc/0x53f0 fs/binfmt_elf.c:864 > > search_binary_handler fs/exec.c:1656 [inline] > > search_binary_handler+0x17f/0x570 fs/exec.c:1634 > > exec_binprm fs/exec.c:1698 [inline] > > __do_execve_file.isra.0+0x1394/0x23f0 fs/exec.c:1818 > > do_execveat_common fs/exec.c:1865 [inline] > > do_execve fs/exec.c:1882 [inline] > > __do_sys_execve fs/exec.c:1958 [inline] > > __se_sys_execve fs/exec.c:1953 [inline] > > __x64_sys_execve+0x8f/0xc0 fs/exec.c:1953 > > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > RIP: 0033:0x7fc7001ba207 > > Code: Bad RIP value. > > RSP: 002b:00007ffe06aa13b8 EFLAGS: 00000206 ORIG_RAX: 000000000000003b > > RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007fc7001ba207 > > RDX: 0000000001fd5fd0 RSI: 00007ffe06aa14b0 RDI: 00007ffe06aa24c0 > > RBP: 0000000000625500 R08: 0000000000001c49 R09: 0000000000001c49 > > R10: 0000000000000000 R11: 0000000000000206 R12: 0000000001fd5fd0 > > R13: 0000000000000007 R14: 0000000001fc6250 R15: 0000000000000005 > > BUG: Bad page state in process udevd pfn:2b13c > > page:ffffea0000ac4f00 count:0 mapcount:0 mapping:ffff88800df2ad40 index:0xe > > shmem_aops > > flags: 0x1fffc000008000c(uptodate|dirty|swapbacked) > > raw: 01fffc000008000c ffff8880a85af890 ffff8880a85af890 ffff88800df2ad40 > > raw: 000000000000000e 0000000000000000 00000000ffffffff 0000000000000000 > > page dumped because: non-NULL mapping > > Modules linked in: > > CPU: 1 PID: 7586 Comm: udevd Tainted: G B > > 5.0.0-rc6-next-20190213 #34 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > Google 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:77 [inline] > > dump_stack+0x172/0x1f0 lib/dump_stack.c:113 > > bad_page.cold+0xda/0xff mm/page_alloc.c:586 > > name:"memfd:" > > free_pages_check_bad+0x142/0x1a0 mm/page_alloc.c:1014 > > free_pages_check mm/page_alloc.c:1023 [inline] > > free_pages_prepare mm/page_alloc.c:1113 [inline] > > free_pcp_prepare mm/page_alloc.c:1138 [inline] > > free_unref_page_prepare mm/page_alloc.c:2991 [inline] > > free_unref_page_list+0x31d/0xc40 mm/page_alloc.c:3060 > > release_pages+0x60d/0x1940 mm/swap.c:791 > > pagevec_lru_move_fn+0x218/0x2a0 mm/swap.c:213 > > __pagevec_lru_add mm/swap.c:917 [inline] > > lru_add_drain_cpu+0x2f7/0x520 mm/swap.c:581 > > lru_add_drain+0x20/0x60 mm/swap.c:652 > > exit_mmap+0x290/0x530 mm/mmap.c:3134 > > __mmput kernel/fork.c:1047 [inline] > > mmput+0x15f/0x4c0 kernel/fork.c:1068 > > exec_mmap fs/exec.c:1046 [inline] > > flush_old_exec+0x8d9/0x1c20 fs/exec.c:1279 > > load_elf_binary+0x9bc/0x53f0 fs/binfmt_elf.c:864 > > search_binary_handler fs/exec.c:1656 [inline] > > search_binary_handler+0x17f/0x570 fs/exec.c:1634 > > exec_binprm fs/exec.c:1698 [inline] > > __do_execve_file.isra.0+0x1394/0x23f0 fs/exec.c:1818 > > do_execveat_common fs/exec.c:1865 [inline] > > do_execve fs/exec.c:1882 [inline] > > __do_sys_execve fs/exec.c:1958 [inline] > > __se_sys_execve fs/exec.c:1953 [inline] > > __x64_sys_execve+0x8f/0xc0 fs/exec.c:1953 > > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > RIP: 0033:0x7fc7001ba207 > > Code: Bad RIP value. > > RSP: 002b:00007ffe06aa13b8 EFLAGS: 00000206 ORIG_RAX: 000000000000003b > > RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007fc7001ba207 > > RDX: 0000000001fd5fd0 RSI: 00007ffe06aa14b0 RDI: 00007ffe06aa24c0 > > RBP: 0000000000625500 R08: 0000000000001c49 R09: 0000000000001c49 > > R10: 0000000000000000 R11: 0000000000000206 R12: 0000000001fd5fd0 > > R13: 0000000000000007 R14: 0000000001fc6250 R15: 0000000000000005 > > > > > > --- > > 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 > > -- > 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/20190213122331.632a4eb1a12b738ef9633855%40linux-foundation.org. > For more options, visit https://groups.google.com/d/optout. It's apparently the bug in the io_uring patchset I reported yesterday (well, I stole it from another open syzbot bug...) and Jens is already planning to fix: https://marc.info/?l=linux-api&m=155115288114046&w=2. Reproducer is similar, and the crash bisects down to the same commit from the io_uring patchset: "block: implement bio helper to add iter bvec pages to bio". - Eric
