==================================================================
BUG: KASAN: use-after-free in get_disk_and_module block/genhd.c:1524 [inline]
BUG: KASAN: use-after-free in exact_lock+0x38/0xc0 block/genhd.c:594
Read of size 8 at addr ffff8881f06334d0 by task syz.1.2576/14229

CPU: 0 PID: 14229 Comm: syz.1.2576 Tainted: G        W         5.4.292-syzkaller-00021-gcd8e74fa0fa3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 __dump_stack+0x1e/0x20 lib/dump_stack.c:77
 dump_stack+0x15b/0x1b8 lib/dump_stack.c:118
 print_address_description+0x8d/0x4c0 mm/kasan/report.c:384
 __kasan_report+0xef/0x120 mm/kasan/report.c:516
 kasan_report+0x30/0x60 mm/kasan/common.c:653
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 get_disk_and_module block/genhd.c:1524 [inline]
 exact_lock+0x38/0xc0 block/genhd.c:594
 kobj_lookup+0x298/0x430 drivers/base/map.c:119
 get_gendisk+0xe9/0x340 block/genhd.c:879
 bdev_get_gendisk fs/block_dev.c:1105 [inline]
 __blkdev_get+0x125/0x1560 fs/block_dev.c:1560
 blkdev_get+0x68/0x380 fs/block_dev.c:1714
 blkdev_open+0x1cb/0x2b0 fs/block_dev.c:1856
 do_dentry_open+0x8b5/0x1030 fs/open.c:806
 vfs_open+0x73/0x80 fs/open.c:920
 do_last fs/namei.c:3565 [inline]
 path_openat+0x2a5e/0x35c0 fs/namei.c:3683
 do_filp_open+0x1ae/0x3f0 fs/namei.c:3713
 do_sys_open+0x2bb/0x5d0 fs/open.c:1123
 ksys_open include/linux/syscalls.h:1388 [inline]
 __do_sys_creat fs/open.c:1181 [inline]
 __se_sys_creat fs/open.c:1179 [inline]
 __x64_sys_creat+0x65/0x70 fs/open.c:1179
 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
RIP: 0033:0x7efd9aaa5969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007efd9910e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007efd9acccfa0 RCX: 00007efd9aaa5969
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00002000000000c0
RBP: 00007efd9ab27ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007efd9acccfa0 R15: 00007ffe47b654c8

Allocated by task 163:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 __kasan_kmalloc+0x162/0x200 mm/kasan/common.c:529
 kasan_slab_alloc+0x12/0x20 mm/kasan/common.c:537
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slub.c:2829 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 __kmalloc_track_caller+0x10d/0x2d0 mm/slub.c:4449
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0xdc/0x500 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1080 [inline]
 alloc_skb_with_frags+0xa2/0x560 net/core/skbuff.c:5881
 sock_alloc_send_pskb+0x81c/0x930 net/core/sock.c:2276
 sock_alloc_send_skb+0x32/0x40 net/core/sock.c:2293
 mld_newpack+0x193/0x9a0 net/ipv6/mcast.c:1607
 add_grhead+0x5e/0x290 net/ipv6/mcast.c:1710
 add_grec+0xd43/0x1100 net/ipv6/mcast.c:1841
 mld_send_cr net/ipv6/mcast.c:1967 [inline]
 mld_ifc_timer_expire+0x770/0xc50 net/ipv6/mcast.c:2474
 call_timer_fn+0x3c/0x380 kernel/time/timer.c:1448
 expire_timers kernel/time/timer.c:1493 [inline]
 __run_timers+0x81d/0xb60 kernel/time/timer.c:1817
 run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1830
 __do_softirq+0x236/0x660 kernel/softirq.c:292

Freed by task 163:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 kasan_set_free_info mm/kasan/common.c:345 [inline]
 __kasan_slab_free+0x1c3/0x280 mm/kasan/common.c:487
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:496
 slab_free_hook mm/slub.c:1455 [inline]
 slab_free_freelist_hook+0xb7/0x180 mm/slub.c:1494
 slab_free mm/slub.c:3080 [inline]
 kfree+0xbe/0x260 mm/slub.c:4071
 skb_free_head net/core/skbuff.c:601 [inline]
 skb_release_data+0x4ea/0x610 net/core/skbuff.c:621
 skb_release_all net/core/skbuff.c:675 [inline]
 __kfree_skb net/core/skbuff.c:689 [inline]
 kfree_skb+0xbc/0x3a0 net/core/skbuff.c:708
 ip6_mc_input+0x23f/0x2a0 net/ipv6/ip6_input.c:550
 dst_input include/net/dst.h:444 [inline]
 ip6_rcv_finish+0x18c/0x360 net/ipv6/ip6_input.c:80
 NF_HOOK include/linux/netfilter.h:303 [inline]
 ipv6_rcv+0xec/0x220 net/ipv6/ip6_input.c:278
 __netif_receive_skb_one_core net/core/dev.c:4991 [inline]
 __netif_receive_skb+0xc8/0x280 net/core/dev.c:5105
 process_backlog+0x363/0x630 net/core/dev.c:5940
 napi_poll net/core/dev.c:6386 [inline]
 net_rx_action+0x447/0xe50 net/core/dev.c:6454
 __do_softirq+0x236/0x660 kernel/softirq.c:292

The buggy address belongs to the object at ffff8881f0633000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1232 bytes inside of
 2048-byte region [ffff8881f0633000, ffff8881f0633800)
The buggy address belongs to the page:
page:ffffea0007c18c00 refcount:1 mapcount:0 mapping:ffff8881f5c0c000 index:0xffff8881f0632000 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 ffffea0007bcdc08 ffffea00076ddc08 ffff8881f5c0c000
raw: ffff8881f0632000 0000000000080006 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC)
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2165 [inline]
 prep_new_page+0x35e/0x370 mm/page_alloc.c:2171
 get_page_from_freelist+0x1296/0x1310 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x202/0x4b0 mm/page_alloc.c:4894
 alloc_slab_page+0x3c/0x3b0 mm/slub.c:343
 allocate_slab mm/slub.c:1683 [inline]
 new_slab+0x93/0x420 mm/slub.c:1749
 new_slab_objects mm/slub.c:2505 [inline]
 ___slab_alloc+0x29e/0x420 mm/slub.c:2667
 __slab_alloc+0x63/0xa0 mm/slub.c:2707
 slab_alloc_node mm/slub.c:2792 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc_trace+0x130/0x290 mm/slub.c:2854
 kmem_cache_alloc_node_trace include/linux/slab.h:444 [inline]
 kmalloc_node include/linux/slab.h:594 [inline]
 kzalloc_node include/linux/slab.h:701 [inline]
 __alloc_disk_node+0x79/0x5c0 block/genhd.c:1477
 loop_add+0x32b/0x780 drivers/block/loop.c:2142
 loop_init+0x1bf/0x1ff drivers/block/loop.c:2387
 do_one_initcall+0x196/0x5c0 init/main.c:1192
 do_initcall_level+0x21b/0x408 init/main.c:1259
 do_initcalls+0x50/0x92 init/main.c:1275
 do_basic_setup+0x88/0x8f init/main.c:1295
 kernel_init_freeable+0x282/0x42f init/main.c:1458
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881f0633380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881f0633400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881f0633480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff8881f0633500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881f0633580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================