KASAN: use-after-free Read in seq_printf (3)

Status: upstream: reported C repro on 2026/10/12 19:47
Reported-by: syzbot+3f14923befdff8a9f03c@syzkaller.appspotmail.com
First crash: 44d, last: 4h17m
▶ ▼ Similar bugs (14)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 KASAN: use-after-free Read in seq_printf (2) 19 syz, C 16 14h00m 19h55m 0/2 upstream: reported C repro on 2026/10/12 05:38
linux-5.15 KASAN: use-after-free Read in seq_printf 19 2 4d15h 19d 0/3 upstream: reported on 2026/09/23 14:29
android-5-10 KASAN: use-after-free Read in seq_printf 19 15 383d 491d 0/2 auto-obsoleted due to no activity on 2025/12/23 06:43
upstream KASAN: slab-out-of-bounds Read in seq_printf fs 19 5 519d 624d 0/29 auto-obsoleted due to no activity on 2025/08/09 17:54
android-6-1 KASAN: slab-out-of-bounds Read in seq_printf 19 2 388d 392d 0/2 auto-obsoleted due to no activity on 2025/12/19 00:57
android-5-10 KASAN: use-after-free Read in seq_printf (2) 19 1 271d 271d 0/2 auto-obsoleted due to no activity on 2026/04/14 16:00
android-6-1 KASAN: use-after-free Read in seq_printf origin:lts 19 syz, C 20 7d18h 18d 0/2 upstream: reported C repro on 2026/09/24 21:21
android-5-15 KASAN: use-after-free Read in seq_printf 19 1 389d 389d 0/2 auto-obsoleted due to no activity on 2025/12/17 23:30
upstream KMSAN: uninit-value in seq_printf (2) fs 7 syz, C 99 1580d 1846d 0/29 auto-closed as invalid on 2022/09/30 02:43
android-6-1 KASAN: slab-out-of-bounds Read in seq_printf (2) 17 1 191d 191d 0/2 auto-obsoleted due to no activity on 2026/07/03 17:29
android-6-12 KASAN: slab-use-after-free Read in seq_printf origin:lts 19 syz, C 12 2h46m 19d 0/1 premoderation: reported C repro on 2026/09/23 06:02
upstream KMSAN: kernel-infoleak in __skb_datagram_iter net 9 68 1112d 1217d 23/29 fixed on 2023/09/28 17:51
upstream KASAN: slab-use-after-free Read in seq_printf prio:high fs 19 90 11h03m 23d 0/29 upstream: reported on 2026/09/19 02:15
linux-6.6 KASAN: slab-use-after-free Read in seq_printf 19 1 48d 48d 0/2 upstream: reported on 2026/08/25 13:48

Sample crash report:
printk: console [ttyS0] disabled
printk: console [ttyS0] enabled
==================================================================
BUG: KASAN: use-after-free in string_nocheck lib/vsprintf.c:641 [inline]
BUG: KASAN: use-after-free in string+0x20f/0x2a0 lib/vsprintf.c:723
Read of size 1 at addr ffff888100dad4d8 by task syz-executor201/297

CPU: 1 PID: 297 Comm: syz-executor201 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x100/0x140 mm/kasan/report.c:452
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:306
 string_nocheck lib/vsprintf.c:641 [inline]
 string+0x20f/0x2a0 lib/vsprintf.c:723
 vsnprintf+0xec5/0x1990 lib/vsprintf.c:2689
 seq_vprintf fs/seq_file.c:398 [inline]
 seq_printf+0x185/0x280 fs/seq_file.c:413
 show_interrupts+0x921/0xa90 kernel/irq/proc.c:526
 seq_read_iter+0x908/0xce0 fs/seq_file.c:272
 proc_reg_read_iter+0x1be/0x290 fs/proc/inode.c:310
 call_read_iter include/linux/fs.h:2066 [inline]
 generic_file_splice_read+0x3ea/0x5f0 fs/splice.c:311
 do_splice_to fs/splice.c:791 [inline]
 splice_direct_to_actor+0x40a/0xb20 fs/splice.c:870
 do_splice_direct+0x1c2/0x2d0 fs/splice.c:979
 do_sendfile+0x8df/0x1040 fs/read_write.c:1257
 __do_sys_sendfile64 fs/read_write.c:1318 [inline]
 __se_sys_sendfile64 fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0x199/0x1f0 fs/read_write.c:1304
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f424033cdf9
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd99a43888 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 636f7270796d2f2e RCX: 00007f424033cdf9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000007
RBP: 0000000000000001 R08: 00007ffd99a439c8 R09: 00007ffd99a439c8
R10: 00000000000007ff R11: 0000000000000246 R12: 00007ffd99a439b8
R13: 0000000000000002 R14: 00007f42403cdca0 R15: 0000200000000004

Allocated by task 0:
(stack is not available)

Freed by task 297:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1600 [inline]
 slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
 slab_free mm/slub.c:3208 [inline]
 kfree+0xc0/0x270 mm/slub.c:4196
 uart_remove_one_port+0x3b8/0x780 drivers/tty/serial/serial_core.c:3104
 serial8250_unregister_port+0xad/0x260 drivers/tty/serial/8250/8250_core.c:1156
 serial_pnp_remove+0x6b/0x90 drivers/tty/serial/8250/8250_pnp.c:498
 pnp_device_remove+0x75/0x250 drivers/pnp/driver.c:131
 __device_release_driver drivers/base/dd.c:-1 [inline]
 device_release_driver_internal+0x531/0x7c0 drivers/base/dd.c:1221
 device_driver_detach+0x3b/0x40 drivers/base/dd.c:1257
 unbind_store+0x2e5/0x300 drivers/base/bus.c:193
 drv_attr_store+0x79/0xa0 drivers/base/bus.c:77
 sysfs_kf_write+0x129/0x150 fs/sysfs/file.c:143
 kernfs_fop_write_iter+0x2bd/0x400 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2072 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x770/0xd70 fs/read_write.c:605
 ksys_write+0x14a/0x260 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:667
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff888100dad4d8
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes inside of
 8-byte region [ffff888100dad4d8, ffff888100dad4e0)
The buggy address belongs to the page:
page:ffffea0004036b40 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888100dadbe0 pfn:0x100dad
flags: 0x4000000000000200(slab)
raw: 4000000000000200 ffffea000411f7c0 0000000900000009 ffff888100043c80
raw: ffff888100dadbe0 0000000080660028 00000001ffffffff 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, ts 2058600849, free_ts 0
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x176/0x190 mm/page_alloc.c:2462
 get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x29a/0x640 mm/page_alloc.c:5384
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1813 [inline]
 new_slab+0x84/0x3f0 mm/slub.c:1874
 new_slab_objects mm/slub.c:2632 [inline]
 ___slab_alloc+0x2f8/0x4c0 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 __kmalloc+0x1f9/0x330 mm/slub.c:4034
 kmalloc include/linux/slab.h:560 [inline]
 acpi_os_allocate include/acpi/platform/aclinuxex.h:52 [inline]
 acpi_ex_allocate_name_string drivers/acpi/acpica/exnames.c:66 [inline]
 acpi_ex_get_name_string+0x5a9/0xca0 drivers/acpi/acpica/exnames.c:367
 acpi_ds_create_operand+0x168/0x8b0 drivers/acpi/acpica/dsutils.c:446
 acpi_ds_create_operands+0x271/0x410 drivers/acpi/acpica/dsutils.c:707
 acpi_ds_eval_buffer_field_operands+0x67/0x300 drivers/acpi/acpica/dsopcode.c:290
 acpi_ds_exec_end_op+0x98f/0x1190 drivers/acpi/acpica/dswexec.c:546
 acpi_ps_parse_loop+0xbff/0x19f0 drivers/acpi/acpica/psloop.c:526
 acpi_ps_parse_aml+0x214/0x9a0 drivers/acpi/acpica/psparse.c:475
 acpi_ps_execute_method+0x681/0x7b0 drivers/acpi/acpica/psxface.c:190
 acpi_ns_evaluate+0x650/0xa20 drivers/acpi/acpica/nseval.c:205
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888100dad380: fc fc fc fa fc fc fc fc fb fc fc fc fc fb fc fc
 ffff888100dad400: fc fc fb fc fc fc fc fb fc fc fc fc fa fc fc fc
>ffff888100dad480: fc fb fc fc fc fc 00 fc fc fc fc fa fc fc fc fc
                                                    ^
 ffff888100dad500: 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc fb
 ffff888100dad580: fc fc fc fc fb fc fc fc fc fb fc fc fc fc fb fc
==================================================================

Crashes (47):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/12 19:43 android13-5.10-lts 437aef3f57e8 745a967f .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/12 21:16 android13-5.10-lts 437aef3f57e8 745a967f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/12 05:04 android13-5.10-lts b677692288f7 4f92358f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/11 07:53 android13-5.10-lts b677692288f7 4f92358f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/09 21:25 android13-5.10-lts b677692288f7 4f92358f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/05 10:47 android13-5.10-lts 42d4fb705937 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/04 23:22 android13-5.10-lts 42d4fb705937 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/04 07:44 android13-5.10-lts 8ddf8d57c49c 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/04 02:25 android13-5.10-lts 8ddf8d57c49c 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/04 01:58 android13-5.10-lts 8ddf8d57c49c 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/03 22:27 android13-5.10-lts 8ddf8d57c49c 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/03 20:51 android13-5.10-lts 8ddf8d57c49c 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/03 17:14 android13-5.10-lts 8ddf8d57c49c 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/02 23:08 android13-5.10-lts df334e630ed3 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/01 19:32 android13-5.10-lts 27ea5541934c f5cdae2f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/01 14:56 android13-5.10-lts 27ea5541934c f5cdae2f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/01 14:25 android13-5.10-lts 27ea5541934c f5cdae2f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/30 18:02 android13-5.10-lts 27ea5541934c 7808aef4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/30 17:42 android13-5.10-lts 27ea5541934c 7808aef4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/30 15:32 android13-5.10-lts 27ea5541934c 7808aef4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/30 14:29 android13-5.10-lts 27ea5541934c 7808aef4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/30 10:59 android13-5.10-lts 27ea5541934c 7808aef4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/30 10:59 android13-5.10-lts 27ea5541934c 7808aef4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/30 10:59 android13-5.10-lts 27ea5541934c 7808aef4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/30 08:33 android13-5.10-lts 27ea5541934c 7808aef4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/30 04:01 android13-5.10-lts 9d97551ff1f9 328436b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/29 20:35 android13-5.10-lts 9d97551ff1f9 328436b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/29 17:43 android13-5.10-lts 9d97551ff1f9 328436b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/29 17:42 android13-5.10-lts 9d97551ff1f9 328436b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/29 16:11 android13-5.10-lts 9d97551ff1f9 7bf4ea23 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/29 13:28 android13-5.10-lts 340d402887d3 7bf4ea23 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/29 13:26 android13-5.10-lts 340d402887d3 7bf4ea23 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/29 08:16 android13-5.10-lts 340d402887d3 7bf4ea23 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/29 08:13 android13-5.10-lts 340d402887d3 7bf4ea23 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/28 21:07 android13-5.10-lts 903d9c6a2636 a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/28 20:57 android13-5.10-lts 903d9c6a2636 a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/28 14:01 android13-5.10-lts c5d8ec7afea2 a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/27 17:22 android13-5.10-lts c5d8ec7afea2 a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/27 03:00 android13-5.10-lts c5d8ec7afea2 a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/25 14:22 android13-5.10-lts 452567d1985b f281d9d2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/24 23:32 android13-5.10-lts 452567d1985b 3c3cdf19 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/24 13:54 android13-5.10-lts 452567d1985b 0281b448 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/23 20:56 android13-5.10-lts 452567d1985b abce1216 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/22 11:14 android13-5.10-lts 452567d1985b e12281bd .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/09/11 18:26 android13-5.10-lts 452567d1985b b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/08/30 00:44 android13-5.10-lts 174d3ccb72b8 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/04 16:57 android13-5.10-lts 42d4fb705937 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: out-of-bounds Read in seq_printf
* Struck through repros no longer work on HEAD.