loop1: rw=524288, sector=1056, nr_sectors = 16 limit=16 syz.1.191: attempt to access beyond end of device loop1: rw=524288, sector=8, nr_sectors = 16 limit=16 ================================================================== BUG: KASAN: use-after-free in memcpy_to_page include/linux/highmem.h:403 [inline] BUG: KASAN: use-after-free in z_erofs_transform_plain+0x39c/0x494 fs/erofs/decompressor.c:347 Read of size 4096 at addr ffff0000dc5f6000 by task syz.1.191/5004 CPU: 1 PID: 5004 Comm: syz.1.191 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/23/2026 Call trace: dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 print_address_description+0x88/0x218 mm/kasan/report.c:316 print_report+0x50/0x68 mm/kasan/report.c:420 kasan_report+0xa8/0xfc mm/kasan/report.c:524 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x258/0x290 mm/kasan/generic.c:189 memcpy+0x48/0x90 mm/kasan/shadow.c:65 memcpy_to_page include/linux/highmem.h:403 [inline] z_erofs_transform_plain+0x39c/0x494 fs/erofs/decompressor.c:347 z_erofs_decompress+0x9c/0xd4 fs/erofs/decompressor.c:435 z_erofs_decompress_pcluster fs/erofs/zdata.c:1161 [inline] z_erofs_decompress_queue+0x103c/0x1bf4 fs/erofs/zdata.c:1242 z_erofs_runqueue+0x1508/0x16a8 fs/erofs/zdata.c:1614 z_erofs_read_folio+0x2dc/0x5cc fs/erofs/zdata.c:1704 filemap_read_folio+0x134/0x384 mm/filemap.c:2490 filemap_update_page mm/filemap.c:2575 [inline] filemap_get_pages mm/filemap.c:2689 [inline] filemap_read+0x1290/0x20dc mm/filemap.c:2759 generic_file_read_iter+0xf8/0x5ac mm/filemap.c:2941 call_read_iter include/linux/fs.h:2265 [inline] new_sync_read fs/read_write.c:389 [inline] vfs_read+0x3cc/0x7b8 fs/read_write.c:470 ksys_read+0x12c/0x228 fs/read_write.c:613 __do_sys_read fs/read_write.c:623 [inline] __se_sys_read fs/read_write.c:621 [inline] __arm64_sys_read+0x7c/0x90 fs/read_write.c:621 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:589 Allocated by task 4959: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:53 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505 __kasan_slab_alloc+0x70/0x88 mm/kasan/common.c:329 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook+0x74/0x430 mm/slab.h:742 slab_alloc_node mm/slub.c:3366 [inline] slab_alloc mm/slub.c:3374 [inline] __kmem_cache_alloc_lru mm/slub.c:3381 [inline] kmem_cache_alloc+0x234/0x310 mm/slub.c:3390 skb_clone+0x194/0x308 net/core/skbuff.c:1663 do_one_broadcast net/netlink/af_netlink.c:1453 [inline] netlink_broadcast+0x580/0x1054 net/netlink/af_netlink.c:1524 uevent_net_broadcast_untagged lib/kobject_uevent.c:331 [inline] kobject_uevent_net_broadcast+0x32c/0x528 lib/kobject_uevent.c:409 kobject_uevent_env+0x550/0x88c lib/kobject_uevent.c:608 kobject_uevent+0x2c/0x3c lib/kobject_uevent.c:657 loop_configure+0xb84/0xf28 drivers/block/loop.c:1109 lo_ioctl+0x19c/0x18a8 drivers/block/loop.c:1565 blkdev_ioctl+0x654/0xb74 block/ioctl.c:626 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:589 Freed by task 3942: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:53 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:237 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:245 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1735 [inline] slab_free_freelist_hook+0x16c/0x1e8 mm/slub.c:1761 slab_free mm/slub.c:3694 [inline] kmem_cache_free+0x118/0x318 mm/slub.c:3716 kfree_skbmem+0x10c/0x198 net/core/skbuff.c:-1 __kfree_skb net/core/skbuff.c:871 [inline] consume_skb+0xa8/0x104 net/core/skbuff.c:1038 skb_free_datagram+0x20/0x30 net/core/datagram.c:322 netlink_recvmsg+0x4a0/0xb08 net/netlink/af_netlink.c:1955 ____sys_recvmsg+0x270/0x754 net/socket.c:-1 ___sys_recvmsg net/socket.c:2780 [inline] __sys_recvmsg+0x250/0x33c net/socket.c:2810 __do_sys_recvmsg net/socket.c:2820 [inline] __se_sys_recvmsg net/socket.c:2817 [inline] __arm64_sys_recvmsg+0x80/0x94 net/socket.c:2817 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:589 The buggy address belongs to the object at ffff0000dc5f6000 which belongs to the cache skbuff_head_cache of size 240 The buggy address is located 0 bytes inside of 240-byte region [ffff0000dc5f6000, ffff0000dc5f60f0) The buggy address belongs to the physical page: page:000000003a0fbac4 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11c5f6 flags: 0x5ffc00000000200(slab|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000000200 0000000000000000 dead000000000122 ffff0000c0bc8180 raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000dc5f5f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff0000dc5f5f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff0000dc5f6000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000dc5f6080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc ffff0000dc5f6100: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ================================================================== syz.1.191: attempt to access beyond end of device loop1: rw=0, sector=1056, nr_sectors = 8 limit=16