On Thu, Dec 28, 2017 at 1:02 PM, syzbot <syzbot+3657e9e2c5ad99152f32@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > Hello, > > syzkaller hit the following crash on > 464e1d5f23cca236b930ef068c328a64cab78fb1 > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.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. > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+3657e9e2c5ad99152f32@xxxxxxxxxxxxxxxxxxxxxxxxx > It will help syzbot understand when the bug is fixed. See footer for > details. > If you forward the report, please keep this part and the footer. > > device gre0 entered promiscuous mode > kasan: CONFIG_KASAN_INLINE enabled > ================================================================== > BUG: KASAN: use-after-free in __fcheck_files include/linux/fdtable.h:85 > [inline] > BUG: KASAN: use-after-free in fcheck_files include/linux/fdtable.h:95 > [inline] > BUG: KASAN: use-after-free in __fget+0x547/0x570 fs/file.c:690 > Read of size 4 at addr ffff8801d4302f00 by task syz-executor4/22370 > > CPU: 0 PID: 22370 Comm: syz-executor4 Not tainted 4.15.0-rc5+ #147 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:17 [inline] > dump_stack+0x194/0x257 lib/dump_stack.c:53 > print_address_description+0x73/0x250 mm/kasan/report.c:252 > kasan_report_error mm/kasan/report.c:351 [inline] > kasan_report+0x25b/0x340 mm/kasan/report.c:409 > __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429 > __fcheck_files include/linux/fdtable.h:85 [inline] > fcheck_files include/linux/fdtable.h:95 [inline] > __fget+0x547/0x570 fs/file.c:690 > __fget_light+0x2eb/0x380 fs/file.c:745 > __fdget+0x18/0x20 fs/file.c:753 > fdget include/linux/file.h:57 [inline] > sockfd_lookup_light+0x21/0x150 net/socket.c:495 > SYSC_sendto+0x144/0x5c0 net/socket.c:1709 > SyS_sendto+0x40/0x50 net/socket.c:1695 > do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline] > do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389 > entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:125 > RIP: 0023:0xf7f53c79 > RSP: 002b:00000000f772e08c EFLAGS: 00000296 ORIG_RAX: 0000000000000171 > RAX: ffffffffffffffda RBX: 0000000000000013 RCX: 0000000020ab7000 > RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000020ab8000 > RBP: 000000000000001c R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > Allocated by task 22368: > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > set_track mm/kasan/kasan.c:459 [inline] > kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 > __do_kmalloc mm/slab.c:3708 [inline] > __kmalloc+0x162/0x760 mm/slab.c:3717 > kmalloc include/linux/slab.h:504 [inline] > kzalloc include/linux/slab.h:688 [inline] > ext4_htree_store_dirent+0x8b/0x580 fs/ext4/dir.c:451 > htree_dirblock_to_tree+0x4e8/0xa00 fs/ext4/namei.c:1019 > ext4_htree_fill_tree+0x2bb/0xcb0 fs/ext4/namei.c:1096 > ext4_dx_readdir fs/ext4/dir.c:575 [inline] > ext4_readdir+0x1d03/0x3050 fs/ext4/dir.c:122 > iterate_dir+0x1ca/0x530 fs/readdir.c:51 > SYSC_getdents fs/readdir.c:231 [inline] > SyS_getdents+0x225/0x450 fs/readdir.c:212 > entry_SYSCALL_64_fastpath+0x1f/0x96 > > Freed by task 22368: > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > set_track mm/kasan/kasan.c:459 [inline] > kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 > __cache_free mm/slab.c:3488 [inline] > kfree+0xd6/0x260 mm/slab.c:3803 > free_rb_tree_fname+0x85/0xe0 fs/ext4/dir.c:403 > ext4_htree_free_dir_info fs/ext4/dir.c:425 [inline] > ext4_release_dir+0x44/0x60 fs/ext4/dir.c:623 > __fput+0x327/0x7e0 fs/file_table.c:210 > ____fput+0x15/0x20 fs/file_table.c:244 > task_work_run+0x199/0x270 kernel/task_work.c:113 > tracehook_notify_resume include/linux/tracehook.h:191 [inline] > exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162 > prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] > syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 > entry_SYSCALL_64_fastpath+0x94/0x96 > > The buggy address belongs to the object at ffff8801d4302f00 > which belongs to the cache kmalloc-64 of size 64 > The buggy address is located 0 bytes inside of > 64-byte region [ffff8801d4302f00, ffff8801d4302f40) > The buggy address belongs to the page: > page:0000000089700587 count:1 mapcount:0 mapping:00000000159189cf > index:0xffff8801d4302400 > flags: 0x2fffc0000000100(slab) > raw: 02fffc0000000100 ffff8801d4302000 ffff8801d4302400 000000010000001b > raw: ffffea00070cfda0 ffffea0006cb16e0 ffff8801db000340 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801d4302e00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > ffff8801d4302e80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >> >> ffff8801d4302f00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > > ^ > ffff8801d4302f80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > ffff8801d4303000: 00 00 00 00 fc fc fc fc 00 00 00 fc fc fc fc fc > ================================================================== This happened only once so far. Can be a subtle race, can be a previous silent memory corruption. So just in case you see something obvious in the code. > --- > 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. > > syzbot will keep track of this bug report. > If you forgot to add the Reported-by tag, once the fix for this bug is > merged > into any tree, please 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/001a113f711a9a1eb10561654867%40google.com. > For more options, visit https://groups.google.com/d/optout.
