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: 64d, last: 8h24m
▶ ▼ Similar bugs (15)
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 22 1d03h 21d 0/2 upstream: reported C repro on 2026/10/12 05:38
linux-6.1 KASAN: use-after-free Read in seq_printf 19 3 9d20h 10d 0/3 upstream: reported on 2026/10/23 08:35
linux-5.15 KASAN: use-after-free Read in seq_printf 19 4 1d12h 40d 0/3 upstream: reported on 2026/09/23 14:29
android-5-10 KASAN: use-after-free Read in seq_printf 19 15 404d 511d 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 539d 645d 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 408d 413d 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 292d 292d 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 24 3d13h 38d 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 409d 409d 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 1601d 1867d 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 212d 212d 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 23 1d14h 40d 0/1 premoderation: reported C repro on 2026/09/23 06:02
upstream KMSAN: kernel-infoleak in __skb_datagram_iter net 9 68 1133d 1238d 23/29 fixed on 2023/09/28 17:51
upstream KASAN: slab-use-after-free Read in seq_printf prio:high fs 19 C 91 4d05h 44d 0/29 upstream: reported C repro on 2026/09/19 02:15
linux-6.6 KASAN: slab-use-after-free Read in seq_printf 19 2 20d 69d 0/2 upstream: reported on 2026/08/25 13:48

Sample crash report:
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 ffff888104fd9c08 by task syz-executor293/297

CPU: 1 PID: 297 Comm: syz-executor293 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
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
 traverse+0x1f2/0x590 fs/seq_file.c:111
 seq_read_iter+0xbcd/0xce0 fs/seq_file.c:195
 proc_reg_read_iter+0x1be/0x290 fs/proc/inode.c:310
 do_iter_readv_writev+0x477/0x5f0 fs/read_write.c:-1
 do_iter_read+0x168/0x5d0 fs/read_write.c:801
 vfs_readv fs/read_write.c:921 [inline]
 do_preadv+0x233/0x390 fs/read_write.c:1013
 __do_sys_preadv fs/read_write.c:1063 [inline]
 __se_sys_preadv fs/read_write.c:1058 [inline]
 __x64_sys_preadv+0x9e/0xb0 fs/read_write.c:1058
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f4ca15a4e39
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:00007ffef9ebc468 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 636f7270796d2f2e RCX: 00007f4ca15a4e39
RDX: 0000000000000001 RSI: 0000200000000140 RDI: 0000000000000006
RBP: 0000000000000001 R08: 0000000000000004 R09: 00007ffef9ebc598
R10: 000000000000ffff R11: 0000000000000246 R12: 00007ffef9ebc588
R13: 0000000000000002 R14: 00007f4ca1635ca0 R15: 0000000000000002

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 ffff888104fd9c08
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes inside of
 8-byte region [ffff888104fd9c08, ffff888104fd9c10)
The buggy address belongs to the page:
page:ffffea000413f640 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888104fd9550 pfn:0x104fd9
flags: 0x4000000000000200(slab)
raw: 4000000000000200 ffffea000419f3c0 0000000b0000000b ffff888100043c80
raw: ffff888104fd9550 0000000080660063 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 17, ts 2531324896, 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_track_caller+0x1e4/0x310 mm/slub.c:4541
 kstrdup mm/util.c:63 [inline]
 kstrdup_const+0x55/0x90 mm/util.c:86
 __kernfs_new_node+0xa6/0x670 fs/kernfs/dir.c:658
 kernfs_new_node+0x150/0x260 fs/kernfs/dir.c:739
 kernfs_create_link+0xa4/0x200 fs/kernfs/symlink.c:39
 sysfs_do_create_link_sd+0x8a/0x110 fs/sysfs/symlink.c:44
 sysfs_do_create_link fs/sysfs/symlink.c:80 [inline]
 sysfs_create_link+0x68/0x80 fs/sysfs/symlink.c:92
 device_create_sys_dev_entry+0x11b/0x180 drivers/base/core.c:3096
 device_add+0x847/0xc00 drivers/base/core.c:3240
 device_create_groups_vargs drivers/base/core.c:3960 [inline]
 device_create+0x26c/0x300 drivers/base/core.c:4002
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888104fd9b00: fc fc fc 00 fc fc fc fc fa fc fc fc fc 00 fc fc
 ffff888104fd9b80: fc fc fb fc fc fc fc 00 fc fc fc fc fa fc fc fc
>ffff888104fd9c00: fc fa fc fc fc fc fa fc fc fc fc 00 fc fc fc fc
                      ^
 ffff888104fd9c80: 00 fc fc fc fc 00 fc fc fc fc fa fc fc fc fc 00
 ffff888104fd9d00: fc fc fc fc fa fc fc fc fc 00 fc fc fc fc 00 fc
=======

Crashes (56):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/31 16:16 android13-5.10-lts f61a392235e0 2041d3f8 .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 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
2026/11/02 09:19 android13-5.10-lts f61a392235e0 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/11/02 05:51 android13-5.10-lts f61a392235e0 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/11/02 01:47 android13-5.10-lts f61a392235e0 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/31 22:51 android13-5.10-lts f61a392235e0 2041d3f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/27 17:17 android13-5.10-lts f61a392235e0 96923c60 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/13 20:54 android13-5.10-lts 390db4f54a67 5a1eeac4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in seq_printf
2026/10/13 07:34 android13-5.10-lts d64ecae82de0 5a1eeac4 .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 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.