==================================================================
BUG: KASAN: slab-use-after-free in flow_block_cb_is_busy net/core/flow_offload.c:326 [inline]
BUG: KASAN: slab-use-after-free in flow_block_cb_setup_simple+0x1b0/0x6ac net/core/flow_offload.c:351
Read of size 8 at addr ffff0000c3781c20 by task syz.0.175/5282

CPU: 0 UID: 0 PID: 5282 Comm: syz.0.175 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/23/2026
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack+0x30/0x40 lib/dump_stack.c:94
 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
 print_address_description+0xb0/0x238 mm/kasan/report.c:378
 print_report+0x68/0x84 mm/kasan/report.c:482
 kasan_report+0x8c/0xc4 mm/kasan/report.c:595
 __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381
 flow_block_cb_is_busy net/core/flow_offload.c:326 [inline]
 flow_block_cb_setup_simple+0x1b0/0x6ac net/core/flow_offload.c:351
 nsim_setup_tc+0xe0/0x238 drivers/net/netdevsim/tc.c:87
 nft_block_offload_cmd net/netfilter/nf_tables_offload.c:397 [inline]
 nft_chain_offload_cmd+0x1c0/0x494 net/netfilter/nf_tables_offload.c:451
 nft_flow_block_chain+0xfc/0x2c8 net/netfilter/nf_tables_offload.c:471
 nft_flow_offload_chain net/netfilter/nf_tables_offload.c:513 [inline]
 nft_flow_rule_offload_commit+0x450/0xae0 net/netfilter/nf_tables_offload.c:-1
 nf_tables_commit+0xc74/0x6b20 net/netfilter/nf_tables_api.c:11006
 nfnetlink_rcv_batch net/netfilter/nfnetlink.c:574 [inline]
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:647 [inline]
 nfnetlink_rcv+0xfb0/0x16ec net/netfilter/nfnetlink.c:665
 netlink_unicast_kernel net/netlink/af_netlink.c:1338 [inline]
 netlink_unicast+0x600/0x7f8 net/netlink/af_netlink.c:1364
 netlink_sendmsg+0x648/0x948 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg+0xc8/0x17c net/socket.c:815
 ____sys_sendmsg+0x3d0/0x6c8 net/socket.c:2713
 ___sys_sendmsg+0x198/0x224 net/socket.c:2767
 __sys_sendmsg+0x158/0x204 net/socket.c:2799
 __do_sys_sendmsg net/socket.c:2804 [inline]
 __se_sys_sendmsg net/socket.c:2802 [inline]
 __arm64_sys_sendmsg+0x88/0x9c net/socket.c:2802
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796
 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606

Allocated by task 5279:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x40/0x78 mm/kasan/common.c:78
 kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:570
 poison_kmalloc_redzone mm/kasan/common.c:409 [inline]
 __kasan_kmalloc+0x9c/0xb4 mm/kasan/common.c:426
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x2f4/0x5fc mm/slub.c:5563
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 flow_block_cb_alloc net/core/flow_offload.c:265 [inline]
 flow_block_cb_setup_simple+0x27c/0x6ac net/core/flow_offload.c:354
 nsim_setup_tc+0xe0/0x238 drivers/net/netdevsim/tc.c:87
 nft_block_offload_cmd net/netfilter/nf_tables_offload.c:397 [inline]
 nft_chain_offload_cmd+0x1c0/0x494 net/netfilter/nf_tables_offload.c:451
 nft_flow_block_chain+0xfc/0x2c8 net/netfilter/nf_tables_offload.c:471
 nft_flow_offload_chain net/netfilter/nf_tables_offload.c:513 [inline]
 nft_flow_rule_offload_commit+0x450/0xae0 net/netfilter/nf_tables_offload.c:-1
 nf_tables_commit+0xc74/0x6b20 net/netfilter/nf_tables_api.c:11006
 nfnetlink_rcv_batch net/netfilter/nfnetlink.c:574 [inline]
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:647 [inline]
 nfnetlink_rcv+0xfb0/0x16ec net/netfilter/nfnetlink.c:665
 netlink_unicast_kernel net/netlink/af_netlink.c:1338 [inline]
 netlink_unicast+0x600/0x7f8 net/netlink/af_netlink.c:1364
 netlink_sendmsg+0x648/0x948 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg+0xc8/0x17c net/socket.c:815
 ____sys_sendmsg+0x3d0/0x6c8 net/socket.c:2713
 ___sys_sendmsg+0x198/0x224 net/socket.c:2767
 __sys_sendmsg+0x158/0x204 net/socket.c:2799
 __do_sys_sendmsg net/socket.c:2804 [inline]
 __se_sys_sendmsg net/socket.c:2802 [inline]
 __arm64_sys_sendmsg+0x88/0x9c net/socket.c:2802
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796
 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606

Freed by task 5279:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x40/0x78 mm/kasan/common.c:78
 kasan_save_free_info+0x54/0x6c mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:264 [inline]
 __kasan_slab_free+0x74/0xa4 mm/kasan/common.c:296
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2748 [inline]
 slab_free mm/slub.c:6509 [inline]
 kfree+0x188/0x658 mm/slub.c:6802
 flow_block_cb_free+0x78/0x8c net/core/flow_offload.c:283
 nft_flow_offload_unbind+0x2dc/0x36c net/netfilter/nf_tables_offload.c:344
 nft_block_setup net/netfilter/nf_tables_offload.c:361 [inline]
 nft_block_offload_cmd net/netfilter/nf_tables_offload.c:401 [inline]
 nft_chain_offload_cmd+0x1e8/0x494 net/netfilter/nf_tables_offload.c:451
 nft_flow_block_chain+0xfc/0x2c8 net/netfilter/nf_tables_offload.c:471
 nft_flow_offload_chain net/netfilter/nf_tables_offload.c:513 [inline]
 nft_flow_rule_offload_commit+0x450/0xae0 net/netfilter/nf_tables_offload.c:-1
 nf_tables_commit+0xc74/0x6b20 net/netfilter/nf_tables_api.c:11006
 nfnetlink_rcv_batch net/netfilter/nfnetlink.c:574 [inline]
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:647 [inline]
 nfnetlink_rcv+0xfb0/0x16ec net/netfilter/nfnetlink.c:665
 netlink_unicast_kernel net/netlink/af_netlink.c:1338 [inline]
 netlink_unicast+0x600/0x7f8 net/netlink/af_netlink.c:1364
 netlink_sendmsg+0x648/0x948 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg+0xc8/0x17c net/socket.c:815
 ____sys_sendmsg+0x3d0/0x6c8 net/socket.c:2713
 ___sys_sendmsg+0x198/0x224 net/socket.c:2767
 __sys_sendmsg+0x158/0x204 net/socket.c:2799
 __do_sys_sendmsg net/socket.c:2804 [inline]
 __se_sys_sendmsg net/socket.c:2802 [inline]
 __arm64_sys_sendmsg+0x88/0x9c net/socket.c:2802
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796
 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606

The buggy address belongs to the object at ffff0000c3781c00
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 32 bytes inside of
 freed 192-byte region [ffff0000c3781c00, ffff0000c3781cc0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff0000c3781300 pfn:0x103781
flags: 0x5ffc00000000200(workingset|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 05ffc00000000200 ffff0000c00013c0 fffffdffc317d1d0 fffffdffc30d52d0
raw: ffff0000c3781300 000000000010000f 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000c3781b00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000c3781b80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff0000c3781c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff0000c3781c80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff0000c3781d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
Unable to handle kernel paging request at virtual address dfff800000000004
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
Mem abort info:
  ESR = 0x0000000096000005
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x05: level 1 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0
[dfff800000000004] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1]  SMP
Modules linked in:
CPU: 0 UID: 0 PID: 5282 Comm: syz.0.175 Tainted: G    B               syzkaller #0 PREEMPT 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/23/2026
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : flow_block_cb_is_busy net/core/flow_offload.c:326 [inline]
pc : flow_block_cb_setup_simple+0x1a0/0x6ac net/core/flow_offload.c:351
lr : flow_block_cb_is_busy net/core/flow_offload.c:325 [inline]
lr : flow_block_cb_setup_simple+0x210/0x6ac net/core/flow_offload.c:351
sp : ffff800097386860
x29: ffff800097386860 x28: dfff800000000000 x27: 1fffe00019c4a801
x26: 0000000000000020 x25: dfff800000000000 x24: ffff0000ce254ec0
x23: 0000000000000000 x22: ffff80008301bf30 x21: ffff0000ce254ec0
x20: ffff800097386ad0 x19: ffff80008a268b60 x18: 000000004ac0ee02
x17: 3d3d3d3d3d3d3d3d x16: 3d3d3d3d3d3d3d3d x15: 3d3d3d3d3d3d3d3d
x14: 00000000000007d4 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: ffff7000115f6121 x9 : 0000000000000000
x8 : 0000000000000004 x7 : 0000000000000000 x6 : ffff800080482944
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000020
x2 : 0000000000000000 x1 : ffff0000ee0f3b00 x0 : 0000000000000000
Call trace:
 flow_block_cb_is_busy net/core/flow_offload.c:326 [inline] (P)
 flow_block_cb_setup_simple+0x1a0/0x6ac net/core/flow_offload.c:351 (P)
 nsim_setup_tc+0xe0/0x238 drivers/net/netdevsim/tc.c:87
 nft_block_offload_cmd net/netfilter/nf_tables_offload.c:397 [inline]
 nft_chain_offload_cmd+0x1c0/0x494 net/netfilter/nf_tables_offload.c:451
 nft_flow_block_chain+0xfc/0x2c8 net/netfilter/nf_tables_offload.c:471
 nft_flow_offload_chain net/netfilter/nf_tables_offload.c:513 [inline]
 nft_flow_rule_offload_commit+0x450/0xae0 net/netfilter/nf_tables_offload.c:-1
 nf_tables_commit+0xc74/0x6b20 net/netfilter/nf_tables_api.c:11006
 nfnetlink_rcv_batch net/netfilter/nfnetlink.c:574 [inline]
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:647 [inline]
 nfnetlink_rcv+0xfb0/0x16ec net/netfilter/nfnetlink.c:665
 netlink_unicast_kernel net/netlink/af_netlink.c:1338 [inline]
 netlink_unicast+0x600/0x7f8 net/netlink/af_netlink.c:1364
 netlink_sendmsg+0x648/0x948 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg+0xc8/0x17c net/socket.c:815
 ____sys_sendmsg+0x3d0/0x6c8 net/socket.c:2713
 ___sys_sendmsg+0x198/0x224 net/socket.c:2767
 __sys_sendmsg+0x158/0x204 net/socket.c:2799
 __do_sys_sendmsg net/socket.c:2804 [inline]
 __se_sys_sendmsg net/socket.c:2802 [inline]
 __arm64_sys_sendmsg+0x88/0x9c net/socket.c:2802
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796
 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606
Code: eb1302ff 54000580 910082fa d343ff48 (38796908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	eb1302ff 	cmp	x23, x19
   4:	54000580 	b.eq	0xb4  // b.none
   8:	910082fa 	add	x26, x23, #0x20
   c:	d343ff48 	lsr	x8, x26, #3
* 10:	38796908 	ldrb	w8, [x8, x25] <-- trapping instruction