On Thu, 19 Jul 2018 11:01:01 -0700 syzbot <syzbot+b173e77096a8ba815511@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 1c34981993da Add linux-next specific files for 20180719 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=16e6ac44400000 > kernel config: https://syzkaller.appspot.com/x/.config?x=7002497517b09aec > dashboard link: https://syzkaller.appspot.com/bug?extid=b173e77096a8ba815511 > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. Thanks. I cc'ed v9fs-developer, optimistically. That list manager is weird :( I'm suspecting v9fs. Does that fs attempt to write to the fs from a kmalloced buffer? Full report below... > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+b173e77096a8ba815511@xxxxxxxxxxxxxxxxxxxxxxxxx > > IPVS: length: 141 != 24 > XFS (loop5): Invalid superblock magic number > ================================================================== > BUG: KASAN: use-after-free in memcpy include/linux/string.h:345 [inline] > BUG: KASAN: use-after-free in iov_iter_copy_from_user_atomic+0xb8d/0xfa0 > lib/iov_iter.c:916 > Read of size 21 at addr ffff880190103660 by task kworker/0:3/4927 > > CPU: 0 PID: 4927 Comm: kworker/0:3 Not tainted 4.18.0-rc5-next-20180719+ #11 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Workqueue: events p9_write_work > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113 > print_address_description+0x6c/0x20b mm/kasan/report.c:256 > kasan_report_error mm/kasan/report.c:354 [inline] > kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412 > check_memory_region_inline mm/kasan/kasan.c:260 [inline] > check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 > memcpy+0x23/0x50 mm/kasan/kasan.c:302 > memcpy include/linux/string.h:345 [inline] > iov_iter_copy_from_user_atomic+0xb8d/0xfa0 lib/iov_iter.c:916 > generic_perform_write+0x469/0x6c0 mm/filemap.c:3058 > __generic_file_write_iter+0x26e/0x630 mm/filemap.c:3175 > ext4_file_write_iter+0x390/0x1450 fs/ext4/file.c:266 > call_write_iter include/linux/fs.h:1826 [inline] > new_sync_write fs/read_write.c:474 [inline] > __vfs_write+0x6af/0x9d0 fs/read_write.c:487 > vfs_write+0x1fc/0x560 fs/read_write.c:549 > kernel_write+0xab/0x120 fs/read_write.c:526 > p9_fd_write net/9p/trans_fd.c:427 [inline] > p9_write_work+0x6f1/0xd50 net/9p/trans_fd.c:476 > process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153 > worker_thread+0x189/0x13c0 kernel/workqueue.c:2296 > kthread+0x345/0x410 kernel/kthread.c:246 > ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415 > > Allocated by task 13072: > save_stack+0x43/0xd0 mm/kasan/kasan.c:448 > set_track mm/kasan/kasan.c:460 [inline] > kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 > __do_kmalloc mm/slab.c:3718 [inline] > __kmalloc+0x14e/0x760 mm/slab.c:3727 > kmalloc include/linux/slab.h:518 [inline] > p9_fcall_alloc+0x1e/0x90 net/9p/client.c:237 > p9_tag_alloc net/9p/client.c:266 [inline] > p9_client_prepare_req.part.8+0x107/0xa00 net/9p/client.c:640 > p9_client_prepare_req net/9p/client.c:675 [inline] > p9_client_rpc+0x242/0x1330 net/9p/client.c:675 > p9_client_version net/9p/client.c:890 [inline] > p9_client_create+0xca4/0x1537 net/9p/client.c:974 > v9fs_session_init+0x21a/0x1a80 fs/9p/v9fs.c:400 > v9fs_mount+0x7c/0x900 fs/9p/vfs_super.c:135 > legacy_get_tree+0x131/0x460 fs/fs_context.c:674 > vfs_get_tree+0x1cb/0x5c0 fs/super.c:1743 > do_new_mount fs/namespace.c:2603 [inline] > do_mount+0x6f2/0x1e20 fs/namespace.c:2927 > ksys_mount+0x12d/0x140 fs/namespace.c:3143 > __do_sys_mount fs/namespace.c:3157 [inline] > __se_sys_mount fs/namespace.c:3154 [inline] > __x64_sys_mount+0xbe/0x150 fs/namespace.c:3154 > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Freed by task 13072: > save_stack+0x43/0xd0 mm/kasan/kasan.c:448 > set_track mm/kasan/kasan.c:460 [inline] > __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 > kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 > __cache_free mm/slab.c:3498 [inline] > kfree+0xd9/0x260 mm/slab.c:3813 > p9_free_req+0xb5/0x120 net/9p/client.c:338 > p9_client_rpc+0xa8e/0x1330 net/9p/client.c:739 > p9_client_version net/9p/client.c:890 [inline] > p9_client_create+0xca4/0x1537 net/9p/client.c:974 > v9fs_session_init+0x21a/0x1a80 fs/9p/v9fs.c:400 > v9fs_mount+0x7c/0x900 fs/9p/vfs_super.c:135 > legacy_get_tree+0x131/0x460 fs/fs_context.c:674 > vfs_get_tree+0x1cb/0x5c0 fs/super.c:1743 > do_new_mount fs/namespace.c:2603 [inline] > do_mount+0x6f2/0x1e20 fs/namespace.c:2927 > ksys_mount+0x12d/0x140 fs/namespace.c:3143 > __do_sys_mount fs/namespace.c:3157 [inline] > __se_sys_mount fs/namespace.c:3154 [inline] > __x64_sys_mount+0xbe/0x150 fs/namespace.c:3154 > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > The buggy address belongs to the object at ffff880190103640 > which belongs to the cache kmalloc-16384 of size 16384 > The buggy address is located 32 bytes inside of > 16384-byte region [ffff880190103640, ffff880190107640) > The buggy address belongs to the page: > page:ffffea0006404000 count:1 mapcount:0 mapping:ffff8801da802200 index:0x0 > compound_mapcount: 0 > flags: 0x2fffc0000010200(slab|head) > raw: 02fffc0000010200 ffffea000643b808 ffffea0006452c08 ffff8801da802200 > raw: 0000000000000000 ffff880190103640 0000000100000001 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff880190103500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff880190103580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > > ffff880190103600: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb > ^ > ffff880190103680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff880190103700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > > --- > 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.
