On Sat, Nov 30, 2019 at 06:13:40PM +0800, Hillf Danton wrote: > > On Fri, 29 Nov 2019 23:19:08 -0800 > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: 81b6b964 Merge branch 'master' of git://git.kernel.org/pub.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=13b27696e00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=773597fe8d7cb41a > > dashboard link: https://syzkaller.appspot.com/bug?extid=c732f8644185de340492 > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > > Unfortunately, I don't have any reproducer for this crash yet. > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+c732f8644185de340492@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > ================================================================== > > BUG: KASAN: use-after-free in xlog_alloc_log+0x1398/0x14b0 > > fs/xfs/xfs_log.c:1495 > > Read of size 8 at addr ffff888068139890 by task syz-executor.3/32544 > > > > CPU: 0 PID: 32544 Comm: syz-executor.3 Not tainted 5.4.0-syzkaller #0 > > 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+0x197/0x210 lib/dump_stack.c:118 > > print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 > > __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506 > > kasan_report+0x12/0x20 mm/kasan/common.c:634 > > __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 > > xlog_alloc_log+0x1398/0x14b0 fs/xfs/xfs_log.c:1495 > > xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599 > > xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811 > > xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732 > > mount_bdev+0x304/0x3c0 fs/super.c:1415 > > xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806 > > legacy_get_tree+0x108/0x220 fs/fs_context.c:647 > > vfs_get_tree+0x8e/0x300 fs/super.c:1545 > > do_new_mount fs/namespace.c:2822 [inline] > > do_mount+0x135a/0x1b50 fs/namespace.c:3142 > > ksys_mount+0xdb/0x150 fs/namespace.c:3351 > > __do_sys_mount fs/namespace.c:3365 [inline] > > __se_sys_mount fs/namespace.c:3362 [inline] > > __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362 > > do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > RIP: 0033:0x45d0ca > > Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 4d 8c fb ff c3 66 2e 0f > > 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff > > ff 0f 83 2a 8c fb ff c3 66 0f 1f 84 00 00 00 00 00 > > RSP: 002b:00007f525b430a88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5 > > RAX: ffffffffffffffda RBX: 00007f525b430b40 RCX: 000000000045d0ca > > RDX: 00007f525b430ae0 RSI: 0000000020000100 RDI: 00007f525b430b00 > > RBP: 0000000000000001 R08: 00007f525b430b40 R09: 00007f525b430ae0 > > R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000004 > > R13: 00000000004ca258 R14: 00000000004e2870 R15: 00000000ffffffff > > > > Allocated by task 32544: > > save_stack+0x23/0x90 mm/kasan/common.c:69 > > set_track mm/kasan/common.c:77 [inline] > > __kasan_kmalloc mm/kasan/common.c:510 [inline] > > __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483 > > kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524 > > __do_kmalloc mm/slab.c:3655 [inline] > > __kmalloc+0x163/0x770 mm/slab.c:3664 > > kmalloc include/linux/slab.h:561 [inline] > > kmem_alloc+0x15b/0x4d0 fs/xfs/kmem.c:21 > > kmem_zalloc fs/xfs/kmem.h:68 [inline] > > xlog_alloc_log+0xcce/0x14b0 fs/xfs/xfs_log.c:1437 > > xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599 > > xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811 > > xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732 > > mount_bdev+0x304/0x3c0 fs/super.c:1415 > > xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806 > > legacy_get_tree+0x108/0x220 fs/fs_context.c:647 > > vfs_get_tree+0x8e/0x300 fs/super.c:1545 > > do_new_mount fs/namespace.c:2822 [inline] > > do_mount+0x135a/0x1b50 fs/namespace.c:3142 > > ksys_mount+0xdb/0x150 fs/namespace.c:3351 > > __do_sys_mount fs/namespace.c:3365 [inline] > > __se_sys_mount fs/namespace.c:3362 [inline] > > __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362 > > do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > Freed by task 32544: > > save_stack+0x23/0x90 mm/kasan/common.c:69 > > set_track mm/kasan/common.c:77 [inline] > > kasan_set_free_info mm/kasan/common.c:332 [inline] > > __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471 > > kasan_slab_free+0xe/0x10 mm/kasan/common.c:480 > > __cache_free mm/slab.c:3425 [inline] > > kfree+0x10a/0x2c0 mm/slab.c:3756 > > kvfree+0x61/0x70 mm/util.c:593 > > kmem_free fs/xfs/kmem.h:61 [inline] > > xlog_alloc_log+0xeb5/0x14b0 fs/xfs/xfs_log.c:1497 > > xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599 > > xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811 > > xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732 > > mount_bdev+0x304/0x3c0 fs/super.c:1415 > > xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806 > > legacy_get_tree+0x108/0x220 fs/fs_context.c:647 > > vfs_get_tree+0x8e/0x300 fs/super.c:1545 > > do_new_mount fs/namespace.c:2822 [inline] > > do_mount+0x135a/0x1b50 fs/namespace.c:3142 > > ksys_mount+0xdb/0x150 fs/namespace.c:3351 > > __do_sys_mount fs/namespace.c:3365 [inline] > > __se_sys_mount fs/namespace.c:3362 [inline] > > __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362 > > do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > The buggy address belongs to the object at ffff888068139800 > > which belongs to the cache kmalloc-1k of size 1024 > > The buggy address is located 144 bytes inside of > > 1024-byte region [ffff888068139800, ffff888068139c00) > > The buggy address belongs to the page: > > page:ffffea0001a04e40 refcount:1 mapcount:0 mapping:ffff8880aa400c40 > > index:0x0 > > raw: 00fffe0000000200 ffffea0002728148 ffffea00015604c8 ffff8880aa400c40 > > raw: 0000000000000000 ffff888068139000 0000000100000002 0000000000000000 > > page dumped because: kasan: bad access detected > > > > Memory state around the buggy address: > > ffff888068139780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > > ffff888068139800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > ffff888068139880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ^ > > ffff888068139900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ffff888068139980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ================================================================== > > Add check of ring end to avoid repeated free. > > --- a/fs/xfs/xfs_log.c > +++ b/fs/xfs/xfs_log.c > @@ -1495,6 +1495,8 @@ out_free_iclog: > prev_iclog = iclog->ic_next; > kmem_free(iclog->ic_data); > kmem_free(iclog); > + if (prev_iclog == log->l_iclog) /* complete ring */ > + break; This is probably true, but I can't review or commit this without an SOB. --D > } > out_free_log: > kmem_free(log); >
