[syzbot] [net?] [usb?] KASAN: slab-use-after-free Read in rtl8150_start_xmit

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c1f49dea2b8f Merge tag 'mm-hotfixes-stable-2026-04-19-00-1..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
console output: https://syzkaller.appspot.com/x/log.txt?x=158822d2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=547af2cd0df5277f
dashboard link: https://syzkaller.appspot.com/bug?extid=3f46c095ac0ca048cb71
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b0b2d34cef3a/disk-c1f49dea.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/54e06fcfd92f/vmlinux-c1f49dea.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0aa8d05931c2/bzImage-c1f49dea.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3f46c0...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in rtl8150_start_xmit+0x71f/0x760 drivers/net/usb/rtl8150.c:712
Read of size 4 at addr ffff88810eb7a930 by task kworker/0:4/5226

CPU: 0 UID: 0 PID: 5226 Comm: kworker/0:4 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: mld mld_ifc_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x13d/0x4b0 mm/kasan/report.c:482
kasan_report+0xdf/0x1d0 mm/kasan/report.c:595
rtl8150_start_xmit+0x71f/0x760 drivers/net/usb/rtl8150.c:712
__netdev_start_xmit include/linux/netdevice.h:5343 [inline]
netdev_start_xmit include/linux/netdevice.h:5352 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x128/0x7a0 net/core/dev.c:3904
sch_direct_xmit+0x194/0x890 net/sched/sch_generic.c:372
__dev_xmit_skb net/core/dev.c:4209 [inline]
__dev_queue_xmit+0x278a/0x4930 net/core/dev.c:4831
dev_queue_xmit include/linux/netdevice.h:3401 [inline]
neigh_resolve_output net/core/neighbour.c:1619 [inline]
neigh_resolve_output+0x51d/0x8f0 net/core/neighbour.c:1599
neigh_output include/net/neighbour.h:556 [inline]
ip6_finish_output2+0xa92/0x1f20 net/ipv6/ip6_output.c:136
__ip6_finish_output+0x359/0xd10 net/ipv6/ip6_output.c:208
ip6_finish_output net/ipv6/ip6_output.c:219 [inline]
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x2a1/0xa50 net/ipv6/ip6_output.c:246
dst_output include/net/dst.h:470 [inline]
NF_HOOK.constprop.0+0x115/0x5a0 include/linux/netfilter.h:318
mld_sendpack+0x923/0xef0 net/ipv6/mcast.c:1855
mld_send_cr net/ipv6/mcast.c:2154 [inline]
mld_ifc_work+0x75a/0xc10 net/ipv6/mcast.c:2693
process_one_work+0xa0e/0x1980 kernel/workqueue.c:3302
process_scheduled_works kernel/workqueue.c:3385 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x69a/0xc80 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>

Allocated by task 5226:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
unpoison_slab_object mm/kasan/common.c:340 [inline]
__kasan_slab_alloc+0x6e/0x70 mm/kasan/common.c:366
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4569 [inline]
slab_alloc_node mm/slub.c:4898 [inline]
kmem_cache_alloc_node_noprof+0x26b/0x6b0 mm/slub.c:4950
__alloc_skb+0x140/0x710 net/core/skbuff.c:702
alloc_skb include/linux/skbuff.h:1383 [inline]
mld_newpack.isra.0+0x18e/0xa30 net/ipv6/mcast.c:1775
add_grhead+0x299/0x340 net/ipv6/mcast.c:1886
add_grec+0x139a/0x1940 net/ipv6/mcast.c:2025
mld_send_cr net/ipv6/mcast.c:2148 [inline]
mld_ifc_work+0x3c5/0xc10 net/ipv6/mcast.c:2693
process_one_work+0xa0e/0x1980 kernel/workqueue.c:3302
process_scheduled_works kernel/workqueue.c:3385 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x69a/0xc80 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 2860:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_mempool_poison_object+0x91/0x150 mm/kasan/common.c:539
kasan_mempool_poison_object include/linux/kasan.h:363 [inline]
napi_skb_cache_put+0x68/0x740 net/core/skbuff.c:1459
net_tx_action+0x2b0/0xf90 net/core/dev.c:5807
handle_softirqs+0x1dd/0x9e0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x160/0x210 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
sysvec_apic_timer_interrupt+0x8f/0xb0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

The buggy address belongs to the object at ffff88810eb7a8c0
which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 112 bytes inside of
freed 232-byte region [ffff88810eb7a8c0, ffff88810eb7a9a8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10eb7a
flags: 0x200000000000000(node=0|zone=2)
page_type: f5(slab)
raw: 0200000000000000 ffff888102e8c8c0 dead000000000100 dead000000000122
raw: 0000000000000000 00000008000c000c 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2971, tgid 2971 (syz-executor), ts 110258130289, free_ts 109191008280
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x153/0x170 mm/page_alloc.c:1858
prep_new_page mm/page_alloc.c:1866 [inline]
get_page_from_freelist+0xf34/0x3a90 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x273/0x28a0 mm/page_alloc.c:5226
alloc_slab_page mm/slub.c:3278 [inline]
allocate_slab mm/slub.c:3467 [inline]
new_slab+0xa6/0x6b0 mm/slub.c:3525
refill_objects+0x277/0x420 mm/slub.c:7251
refill_sheaf mm/slub.c:2816 [inline]
__pcs_replace_empty_main+0x375/0x650 mm/slub.c:4651
alloc_from_pcs mm/slub.c:4749 [inline]
slab_alloc_node mm/slub.c:4883 [inline]
kmem_cache_alloc_noprof+0x520/0x6a0 mm/slub.c:4905
skb_clone+0x190/0x400 net/core/skbuff.c:2107
dev_queue_xmit_nit+0x255/0xa80 net/core/dev.c:2574
xmit_one net/core/dev.c:3884 [inline]
dev_hard_start_xmit+0x2fc/0x7a0 net/core/dev.c:3904
sch_direct_xmit+0x194/0x890 net/sched/sch_generic.c:372
__dev_xmit_skb net/core/dev.c:4209 [inline]
__dev_queue_xmit+0x278a/0x4930 net/core/dev.c:4831
dev_queue_xmit include/linux/netdevice.h:3401 [inline]
neigh_hh_output include/net/neighbour.h:540 [inline]
neigh_output include/net/neighbour.h:554 [inline]
ip_finish_output2+0xea0/0x2350 net/ipv4/ip_output.c:237
__ip_finish_output.part.0+0x1b4/0x350 net/ipv4/ip_output.c:315
__ip_finish_output net/ipv4/ip_output.c:303 [inline]
ip_finish_output net/ipv4/ip_output.c:325 [inline]
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x392/0xc00 net/ipv4/ip_output.c:438
dst_output include/net/dst.h:470 [inline]
ip_local_out+0x193/0x1f0 net/ipv4/ip_output.c:131
page last free pid 5250 tgid 5248 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1402 [inline]
__free_frozen_pages+0x692/0xf10 mm/page_alloc.c:2943
tlb_batch_list_free mm/mmu_gather.c:161 [inline]
tlb_finish_mmu+0x27d/0x810 mm/mmu_gather.c:552
exit_mmap+0x454/0xa10 mm/mmap.c:1313
__mmput kernel/fork.c:1178 [inline]
mmput+0xe0/0x430 kernel/fork.c:1201
exit_mm kernel/exit.c:581 [inline]
do_exit+0x833/0x2a60 kernel/exit.c:963
do_group_exit+0xd5/0x2a0 kernel/exit.c:1117
get_signal+0x1ec7/0x21e0 kernel/signal.c:3037
arch_do_signal_or_restart+0x91/0x7a0 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
exit_to_user_mode_loop+0x7e/0x430 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:328 [inline]
do_syscall_64+0x682/0x7f0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff88810eb7a800: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
ffff88810eb7a880: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
>ffff88810eb7a900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88810eb7a980: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
ffff88810eb7aa00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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