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

Status: upstream: reported C repro on 2026/08/04 21:24
Reported-by: syzbot+5916dc0ad70b3adbefcd@syzkaller.appspotmail.com
First crash: 6d20h, last: 2d07h
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in rc_dev_uevent media prio:high 19 syz, C 51 1d00h 5d19h 0/29 upstream: reported C repro on 2026/08/05 22:44
linux-6.1 KASAN: use-after-free Read in rc_dev_uevent 19 syz, C 12 1d10h 6d16h 0/3 upstream: reported C repro on 2026/08/05 01:50
linux-5.15 KASAN: use-after-free Read in rc_dev_uevent 19 syz, C 4 2d19h 6d22h 0/3 upstream: reported C repro on 2026/08/04 19:34

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in string_nocheck lib/vsprintf.c:645 [inline]
BUG: KASAN: slab-use-after-free in string+0x204/0x290 lib/vsprintf.c:727
Read of size 1 at addr ffff88805e400760 by task udevd/5138

CPU: 0 PID: 5138 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 string_nocheck lib/vsprintf.c:645 [inline]
 string+0x204/0x290 lib/vsprintf.c:727
 vsnprintf+0xf72/0x1ba0 lib/vsprintf.c:2823
 add_uevent_var+0x1d1/0x460 lib/kobject_uevent.c:680
 rc_dev_uevent+0x15f/0x190 drivers/media/rc/rc-main.c:1632
 dev_uevent+0x53a/0x7c0 drivers/base/core.c:2659
 uevent_show+0x196/0x300 drivers/base/core.c:2706
 dev_attr_show+0x54/0xc0 drivers/base/core.c:2379
 sysfs_kf_seq_show+0x34d/0x4c0 fs/sysfs/file.c:59
 seq_read_iter+0x464/0xc50 fs/seq_file.c:230
 call_read_iter include/linux/fs.h:2012 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x486/0x990 fs/read_write.c:470
 ksys_read+0x151/0x260 fs/read_write.c:613
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f05eb4a7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffe86429080 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f05ebbb5880 RCX: 00007f05eb4a7407
RDX: 0000000000001000 RSI: 000055a15d8e3560 RDI: 000000000000000c
RBP: 00007f05eb5efff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000a
R13: 00007f05eb5efea0 R14: 0000000000000000 R15: 000055a15d8d47a0
 </TASK>

Allocated by task 5780:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 redrat3_dev_probe+0x3f9/0x23d0 drivers/media/rc/redrat3.c:1025
 usb_probe_interface+0x5c2/0xaf0 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x247/0xae0 drivers/base/dd.c:717
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:879
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:909
 __device_attach_driver+0x2ca/0x510 drivers/base/dd.c:1037
 bus_for_each_drv+0x252/0x2e0 drivers/base/bus.c:459
 __device_attach+0x2c1/0x420 drivers/base/dd.c:1109
 bus_probe_device+0x180/0x260 drivers/base/bus.c:580
 device_add+0x87c/0xc40 drivers/base/core.c:3700
 usb_set_configuration+0x1ad0/0x2150 drivers/usb/core/message.c:2265
 usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x12a/0x260 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x247/0xae0 drivers/base/dd.c:717
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:879
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:909
 __device_attach_driver+0x2ca/0x510 drivers/base/dd.c:1037
 bus_for_each_drv+0x252/0x2e0 drivers/base/bus.c:459
 __device_attach+0x2c1/0x420 drivers/base/dd.c:1109
 bus_probe_device+0x180/0x260 drivers/base/bus.c:580
 device_add+0x87c/0xc40 drivers/base/core.c:3700
 usb_new_device+0x995/0x1550 drivers/usb/core/hub.c:2660
 hub_port_connect drivers/usb/core/hub.c:5529 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5669 [inline]
 port_event drivers/usb/core/hub.c:5833 [inline]
 hub_event+0x29d5/0x4a80 drivers/usb/core/hub.c:5915
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

Freed by task 5780:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1811 [inline]
 slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837
 slab_free mm/slub.c:3830 [inline]
 __kmem_cache_free+0xba/0x1f0 mm/slub.c:3843
 redrat3_delete drivers/media/rc/redrat3.c:466 [inline]
 redrat3_dev_probe+0x1b73/0x23d0 drivers/media/rc/redrat3.c:1126
 usb_probe_interface+0x5c2/0xaf0 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x247/0xae0 drivers/base/dd.c:717
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:879
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:909
 __device_attach_driver+0x2ca/0x510 drivers/base/dd.c:1037
 bus_for_each_drv+0x252/0x2e0 drivers/base/bus.c:459
 __device_attach+0x2c1/0x420 drivers/base/dd.c:1109
 bus_probe_device+0x180/0x260 drivers/base/bus.c:580
 device_add+0x87c/0xc40 drivers/base/core.c:3700
 usb_set_configuration+0x1ad0/0x2150 drivers/usb/core/message.c:2265
 usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x12a/0x260 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x247/0xae0 drivers/base/dd.c:717
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:879
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:909
 __device_attach_driver+0x2ca/0x510 drivers/base/dd.c:1037
 bus_for_each_drv+0x252/0x2e0 drivers/base/bus.c:459
 __device_attach+0x2c1/0x420 drivers/base/dd.c:1109
 bus_probe_device+0x180/0x260 drivers/base/bus.c:580
 device_add+0x87c/0xc40 drivers/base/core.c:3700
 usb_new_device+0x995/0x1550 drivers/usb/core/hub.c:2660
 hub_port_connect drivers/usb/core/hub.c:5529 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5669 [inline]
 port_event drivers/usb/core/hub.c:5833 [inline]
 hub_event+0x29d5/0x4a80 drivers/usb/core/hub.c:5915
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

The buggy address belongs to the object at ffff88805e400000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1888 bytes inside of
 freed 2048-byte region [ffff88805e400000, ffff88805e400800)

The buggy address belongs to the physical page:
page:ffffea0001790000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5e400
head:ffffea0001790000 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017c42000 0000000000000000 0000000000000001
raw: 0000000000000000 0000000000080008 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5809, tgid 5809 (kworker/0:3), ts 99341093012, free_ts 29748627040
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582
 prep_new_page mm/page_alloc.c:1589 [inline]
 get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501
 alloc_slab_page+0x5d/0x180 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:2081
 ___slab_alloc+0xc5c/0x12f0 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x11f/0x250 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc_node_track_caller+0xa4/0x230 mm/slab_common.c:1027
 kmalloc_reserve+0x116/0x240 net/core/skbuff.c:584
 __alloc_skb+0x138/0x2c0 net/core/skbuff.c:653
 alloc_skb include/linux/skbuff.h:1316 [inline]
 mld_newpack+0x14f/0xbf0 net/ipv6/mcast.c:1771
 add_grhead net/ipv6/mcast.c:1882 [inline]
 add_grec+0x1461/0x19c0 net/ipv6/mcast.c:2021
 mld_send_initial_cr+0x288/0x540 net/ipv6/mcast.c:2264
 mld_dad_work+0x3d/0x470 net/ipv6/mcast.c:2290
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459
 free_contig_range+0xa1/0x150 mm/page_alloc.c:6421
 destroy_args+0x7d/0x840 mm/debug_vm_pgtable.c:1015
 debug_vm_pgtable+0x411/0x440 mm/debug_vm_pgtable.c:1400
 do_one_initcall+0x242/0x790 init/main.c:1210
 do_initcall_level+0x13d/0x1f0 init/main.c:1272
 do_initcalls+0x69/0xd0 init/main.c:1288
 kernel_init_freeable+0x3d9/0x560 init/main.c:1525
 kernel_init+0x1d/0x1c0 init/main.c:1415
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

Memory state around the buggy address:
 ffff88805e400600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805e400680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88805e400700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff88805e400780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805e400800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (13):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/09 10:22 linux-6.6.y 6436c12a2ced 5d63f80b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/05 15:10 linux-6.6.y aa0e49877a2e 52aa2820 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/05 08:25 linux-6.6.y aa0e49877a2e 52aa2820 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/05 05:30 linux-6.6.y aa0e49877a2e 52aa2820 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/05 05:30 linux-6.6.y aa0e49877a2e 52aa2820 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/05 01:19 linux-6.6.y aa0e49877a2e d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/05 00:00 linux-6.6.y aa0e49877a2e d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/04 23:13 linux-6.6.y aa0e49877a2e d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/04 22:16 linux-6.6.y aa0e49877a2e d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/04 22:15 linux-6.6.y aa0e49877a2e d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/04 22:13 linux-6.6.y aa0e49877a2e d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/04 21:25 linux-6.6.y aa0e49877a2e d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
2026/08/04 21:23 linux-6.6.y aa0e49877a2e d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in rc_dev_uevent
* Struck through repros no longer work on HEAD.