Hello, syzbot found the following issue on: HEAD commit: 93129492 Add linux-next specific files for 20210326 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=1372ce62d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=4c9322cd4e3b7a16 dashboard link: https://syzkaller.appspot.com/bug?extid=7d6c5587ec9cff5be65c syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1433834ed00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=149c71aad00000 The issue was bisected to: commit daaedb820ad716e00210af8859b194c404202b78 Author: Christoph Hellwig <hch@xxxxxx> Date: Tue Nov 3 10:00:09 2020 +0000 mtd_blkdevs: don't override BLKFLSBUF bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=102c6ddcd00000 final oops: https://syzkaller.appspot.com/x/report.txt?x=122c6ddcd00000 console output: https://syzkaller.appspot.com/x/log.txt?x=142c6ddcd00000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+7d6c5587ec9cff5be65c@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: daaedb820ad7 ("mtd_blkdevs: don't override BLKFLSBUF") ================================================================== BUG: KASAN: use-after-free in kobject_put+0x493/0x540 lib/kobject.c:749 Read of size 1 at addr ffff8880135d453c by task syz-executor372/8533 CPU: 0 PID: 8533 Comm: syz-executor372 Not tainted 5.12.0-rc4-next-20210326-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232 __kasan_report mm/kasan/report.c:399 [inline] kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416 kobject_put+0x493/0x540 lib/kobject.c:749 delete_partition+0xa4/0x170 block/partitions/core.c:291 bdev_del_partition+0xf5/0x110 block/partitions/core.c:474 blkpg_do_ioctl+0x2e8/0x340 block/ioctl.c:33 blkpg_ioctl block/ioctl.c:60 [inline] blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548 block_ioctl+0xf9/0x140 fs/block_dev.c:1667 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x444329 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffdd8945e58 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000487072 RCX: 0000000000444329 RDX: 0000000020000240 RSI: 0000000000001269 RDI: 0000000000000004 RBP: 0000000000000000 R08: 0023706f6f6c2f76 R09: 0000000000000001 R10: 000000000000001f R11: 0000000000000246 R12: 0000000000012734 R13: 00007ffdd8945e6c R14: 00007ffdd8945e80 R15: 00007ffdd8945e70 Allocated by task 8534: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:428 [inline] ____kasan_kmalloc mm/kasan/common.c:507 [inline] ____kasan_kmalloc mm/kasan/common.c:466 [inline] __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:516 kmalloc include/linux/slab.h:556 [inline] kzalloc include/linux/slab.h:686 [inline] kobject_create lib/kobject.c:784 [inline] kobject_create_and_add+0x42/0xb0 lib/kobject.c:810 add_partition+0x56c/0x880 block/partitions/core.c:384 bdev_add_partition+0xb6/0x130 block/partitions/core.c:449 blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43 blkpg_ioctl block/ioctl.c:60 [inline] blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548 block_ioctl+0xf9/0x140 fs/block_dev.c:1667 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 8534: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357 ____kasan_slab_free mm/kasan/common.c:360 [inline] ____kasan_slab_free mm/kasan/common.c:325 [inline] __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:368 kasan_slab_free include/linux/kasan.h:212 [inline] slab_free_hook mm/slub.c:1578 [inline] slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1603 slab_free mm/slub.c:3163 [inline] kfree+0xe5/0x7f0 mm/slub.c:4230 kobject_cleanup lib/kobject.c:705 [inline] kobject_release lib/kobject.c:736 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1c8/0x540 lib/kobject.c:753 delete_partition+0xa4/0x170 block/partitions/core.c:291 bdev_del_partition+0xf5/0x110 block/partitions/core.c:474 blkpg_do_ioctl+0x2e8/0x340 block/ioctl.c:33 blkpg_ioctl block/ioctl.c:60 [inline] blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548 block_ioctl+0xf9/0x140 fs/block_dev.c:1667 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff8880135d4500 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 60 bytes inside of 64-byte region [ffff8880135d4500, ffff8880135d4540) The buggy address belongs to the page: page:ffffea00004d7500 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x135d4 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 0000000000000000 0000000100000001 ffff888010841640 raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880135d4400: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff8880135d4480: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >ffff8880135d4500: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ffff8880135d4580: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc ffff8880135d4600: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ================================================================== --- This report 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 issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches
