KASAN: slab-use-after-free Read in memstick_next_req

Status: upstream: reported on 2026/09/28 00:13
Subsystems: mmc
Labels: prio:high actionable
[Documentation on labels]
Reported-by: syzbot+34f63c11dab47d09ad9a@syzkaller.appspotmail.com
First crash: 4d04h, last: 4d04h
▶ ▼ ✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision
8533ff08 moderation Actionable: ✅ ❓ KASAN: slab-use-after-free Read in memstick_next_req 2026/09/28 00:00 2026/09/28 00:00 2026/09/28 00:12 a3c7249d
a80b9937 repro-c Reproduced: ✅ ❓ KASAN: slab-use-after-free Read in memstick_next_req 2026/09/26 18:07 2026/09/26 18:07 2026/09/26 22:45 a3c7249d
20105836 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ✅ ❓ KASAN: slab-use-after-free Read in memstick_next_req 2026/09/25 00:00 2026/09/25 00:00 2026/09/25 00:34 3c3cdf19
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [mmc?] KASAN: slab-use-after-free Read in memstick_next_req 0 (1) 2026/09/28 00:13
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/09/26 22:59 18m retest repro https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git d58dffe9ee2c8883193959ff4ef995ec07932874 report job log log

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in memstick_next_req+0x1f4/0x240 drivers/memstick/core/memstick.c:227
Read of size 4 at addr ffff888113453074 by task kworker/1:2/15608

CPU: 1 UID: 0 PID: 15608 Comm: kworker/1:2 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Workqueue: events rtsx_usb_ms_handle_req
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/0x1c0 mm/kasan/report.c:595
 memstick_next_req+0x1f4/0x240 drivers/memstick/core/memstick.c:227
 rtsx_usb_ms_handle_req+0x1dc/0x1a00 drivers/memstick/host/rtsx_usb_ms.c:520
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
 process_scheduled_works kernel/workqueue.c:3479 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x69f/0xc90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 9796:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x2d8/0x680 mm/slub.c:5563
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 memstick_alloc_card drivers/memstick/core/memstick.c:383 [inline]
 memstick_check+0x2c1/0x10d0 drivers/memstick/core/memstick.c:452
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
 process_scheduled_works kernel/workqueue.c:3479 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x69f/0xc90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 9796:
 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_slab_free+0x43/0x70 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2748 [inline]
 slab_free mm/slub.c:6499 [inline]
 kfree+0x20c/0x650 mm/slub.c:6792
 memstick_alloc_card drivers/memstick/core/memstick.c:420 [inline]
 memstick_check+0x72b/0x10d0 drivers/memstick/core/memstick.c:452
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
 process_scheduled_works kernel/workqueue.c:3479 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x69f/0xc90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888113453000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 116 bytes inside of
 freed 2048-byte region [ffff888113453000, ffff888113453800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x113450
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x200000000000040(head|node=0|zone=2)
page_type: f5(slab)
raw: 0200000000000040 ffff888100042000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 0200000000000040 ffff888100042000 dead000000000100 dead000000000122
head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 0200000000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
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), pid 2979, tgid 2979 (syz-executor), ts 50665226939
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871
 prep_new_page mm/page_alloc.c:1879 [inline]
 get_page_from_freelist+0xf4b/0x3440 mm/page_alloc.c:3943
 __alloc_frozen_pages_noprof+0x2d7/0x2f70 mm/page_alloc.c:5436
 alloc_slab_page mm/slub.c:3347 [inline]
 allocate_slab mm/slub.c:3462 [inline]
 new_slab+0xa9/0x6e0 mm/slub.c:3513
 refill_objects+0xe3/0x410 mm/slub.c:7410
 refill_sheaf mm/slub.c:2885 [inline]
 __pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4774
 alloc_from_pcs mm/slub.c:4850 [inline]
 slab_alloc_node mm/slub.c:4984 [inline]
 __do_kmalloc_node mm/slub.c:5413 [inline]
 __kmalloc_noprof+0x61c/0x7e0 mm/slub.c:5439
 _kmalloc_noprof include/linux/slab.h:995 [inline]
 sk_prot_alloc+0x10b/0x2a0 net/core/sock.c:2251
 sk_alloc+0x36/0xe80 net/core/sock.c:2307
 __netlink_create+0x5e/0x2c0 net/netlink/af_netlink.c:627
 __netlink_kernel_create+0xed/0x750 net/netlink/af_netlink.c:2024
 netlink_kernel_create include/linux/netlink.h:62 [inline]
 diag_net_init+0xbd/0x140 net/core/sock_diag.c:333
 ops_init+0x1e2/0x5f0 net/core/net_namespace.c:137
 setup_net+0x118/0x3a0 net/core/net_namespace.c:443
 copy_net_ns+0x345/0x7a0 net/core/net_namespace.c:582
 create_new_namespaces+0x3ea/0xac0 kernel/nsproxy.c:132
page last free pid 2979 tgid 2979 ts 50662397831 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1418 [inline]
 __free_frozen_pages+0x714/0xfc0 mm/page_alloc.c:2962
 rcu_do_batch kernel/rcu/tree.c:2650 [inline]
 rcu_core+0x5f0/0x1260 kernel/rcu/tree.c:2919
 handle_softirqs+0x1d9/0x9b0 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 invoke_softirq kernel/softirq.c:519 [inline]
 __irq_exit_rcu+0x168/0x210 kernel/softirq.c:758
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:775
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x8f/0xb0 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674

Memory state around the buggy address:
 ffff888113452f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888113452f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888113453000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                             ^
 ffff888113453080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888113453100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/23 22:58 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing d58dffe9ee2c abce1216 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-usb KASAN: slab-use-after-free Read in memstick_next_req
* Struck through repros no longer work on HEAD.