================================================================== BUG: KASAN: use-after-free in string_nocheck+0x1e4/0x210 lib/vsprintf.c:605 Read of size 1 at addr ffff8880a0fb6f00 by task syz-executor.5/9374 CPU: 1 PID: 9374 Comm: syz-executor.5 Not tainted 5.2.0-rc4 #44 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 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 kasan_report+0x12/0x20 mm/kasan/common.c:614 __asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:129 string_nocheck+0x1e4/0x210 lib/vsprintf.c:605 string+0xed/0x100 lib/vsprintf.c:668 vsnprintf+0x97b/0x19a0 lib/vsprintf.c:2503 vscnprintf lib/vsprintf.c:2606 [inline] scnprintf+0xbb/0x140 lib/vsprintf.c:2660 blkcg_print_stat+0x1f2/0xb30 block/blk-cgroup.c:958 cgroup_seqfile_show+0x1ae/0x310 kernel/cgroup/cgroup.c:3783 kernfs_seq_show+0x14f/0x1b0 fs/kernfs/file.c:167 seq_read+0x4ca/0x1110 fs/seq_file.c:229 kernfs_fop_read+0xed/0x560 fs/kernfs/file.c:251 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x4a4/0x660 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:997 do_readv+0x15b/0x330 fs/read_write.c:1034 __do_sys_readv fs/read_write.c:1125 [inline] __se_sys_readv fs/read_write.c:1122 [inline] __x64_sys_readv+0x75/0xb0 fs/read_write.c:1122 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459279 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f0e27f58c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000013 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459279 RDX: 000000000000017c RSI: 00000000200002c0 RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0e27f596d4 R13: 00000000004c6392 R14: 00000000004db1c0 R15: 00000000ffffffff Allocated by task 9703: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_kmalloc mm/kasan/common.c:489 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503 __do_kmalloc mm/slab.c:3660 [inline] __kmalloc_track_caller+0x158/0x740 mm/slab.c:3675 kvasprintf+0xc8/0x170 lib/kasprintf.c:25 kvasprintf_const+0x65/0x190 lib/kasprintf.c:49 kobject_set_name_vargs+0x5b/0x150 lib/kobject.c:289 device_create_groups_vargs+0x1bb/0x270 drivers/base/core.c:2712 device_create_vargs+0x45/0x60 drivers/base/core.c:2756 bdi_register_va.part.0+0x38/0x740 mm/backing-dev.c:883 bdi_register_va mm/backing-dev.c:911 [inline] bdi_register+0x12a/0x140 mm/backing-dev.c:908 bdi_register_owner+0x6a/0x110 mm/backing-dev.c:918 __device_add_disk+0xdb1/0x11c0 block/genhd.c:730 device_add_disk+0x2b/0x40 block/genhd.c:754 add_disk include/linux/genhd.h:429 [inline] loop_add+0x635/0x8d0 drivers/block/loop.c:2056 loop_probe+0x161/0x1a0 drivers/block/loop.c:2128 kobj_lookup+0x260/0x460 drivers/base/map.c:124 get_gendisk+0x4d/0x390 block/genhd.c:869 bdev_get_gendisk fs/block_dev.c:1112 [inline] __blkdev_get+0x457/0x1660 fs/block_dev.c:1505 blkdev_get+0xc4/0x990 fs/block_dev.c:1664 blkdev_open+0x205/0x290 fs/block_dev.c:1822 do_dentry_open+0x4df/0x1250 fs/open.c:778 vfs_open+0xa0/0xd0 fs/open.c:887 do_last fs/namei.c:3416 [inline] path_openat+0x10e9/0x46d0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1070 __do_sys_open fs/open.c:1088 [inline] __se_sys_open fs/open.c:1083 [inline] __x64_sys_open+0x7e/0xc0 fs/open.c:1083 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9383: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459 __cache_free mm/slab.c:3432 [inline] kfree+0xcf/0x220 mm/slab.c:3755 kfree_const+0x59/0x70 mm/util.c:32 kobject_cleanup lib/kobject.c:697 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put.cold+0x2b3/0x2e6 lib/kobject.c:737 put_device drivers/base/core.c:2210 [inline] device_unregister+0x28/0x40 drivers/base/core.c:2307 bdi_unregister+0x41c/0x5e0 mm/backing-dev.c:950 del_gendisk+0x896/0xb30 block/genhd.c:801 loop_remove+0x3c/0xd0 drivers/block/loop.c:2074 loop_control_ioctl drivers/block/loop.c:2173 [inline] loop_control_ioctl+0x320/0x360 drivers/block/loop.c:2139 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:696 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880a0fb6f00 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 0 bytes inside of 32-byte region [ffff8880a0fb6f00, ffff8880a0fb6f20) The buggy address belongs to the page: page:ffffea000283ed80 refcount:1 mapcount:0 mapping:ffff8880aa4001c0 index:0xffff8880a0fb6fc1 flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea0002a0c608 ffffea000280e488 ffff8880aa4001c0 raw: ffff8880a0fb6fc1 ffff8880a0fb6000 000000010000003a 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a0fb6e00: fb fb fb fb fc fc fc fc 00 00 00 00 fc fc fc fc ffff8880a0fb6e80: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc >ffff8880a0fb6f00: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc ^ ffff8880a0fb6f80: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880a0fb7000: 00 00 00 00 00 fc fc 00 00 00 00 00 fc fc 00 00 ==================================================================