KASAN: use-after-free Write in ring_buffer_read_page

Status: upstream: reported on 2026/06/02 13:45
Subsystems: trace
Labels: actionable prio:normal
[Documentation on labels]
Reported-by: syzbot+2dd9d02f60775ce5c1fb@syzkaller.appspotmail.com
First crash: 74d, last: 74d
▶ ▼ ✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision
b2620161 repro-c Reproduced: ✅
❓ KASAN: use-after-free Write in ring_buffer_read_page 2026/06/02 16:30 2026/06/02 17:00 2026/06/02 18:12 62fe1528
f8d8a18a assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: use-after-free Write in ring_buffer_read_page 2026/06/02 12:55 2026/06/02 12:55 2026/06/02 14:00 1095583b
a0cf1c5b moderation Actionable: ✅ ❓ KASAN: use-after-free Write in ring_buffer_read_page 2026/06/02 12:54 2026/06/02 12:54 2026/06/02 13:44 1095583b
▶ ▼ Discussions (4)
Title Replies (including bot) Last reply
[for-linus][PATCH 05/13] ring_buffer: Check page order under reader_lock 2 (2) 2026/07/07 14:37
[PATCH] ring-buffer: serialize read-page order with subbuffer resize 4 (4) 2026/06/30 20:45
[PATCH] tracing: ring_buffer: Check page order under reader_lock 1 (1) 2026/06/11 15:17
[syzbot] [trace?] KASAN: use-after-free Write in ring_buffer_read_page 5 (6) 2026/06/08 14:01
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/08/07 09:09 23m glider@google.com upstream report log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in ring_buffer_read_page+0xd51/0x15a0 kernel/trace/ring_buffer.c:7059
Write of size 16308 at addr ffff88805ceb404c by task syz.3.1872/14532

CPU: 0 UID: 0 PID: 14532 Comm: syz.3.1872 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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
 check_region_inline mm/kasan/generic.c:186 [inline]
 kasan_check_range+0x10f/0x1e0 mm/kasan/generic.c:200
 __asan_memset+0x23/0x50 mm/kasan/shadow.c:84
 ring_buffer_read_page+0xd51/0x15a0 kernel/trace/ring_buffer.c:7059
 tracing_buffers_read+0x2bf/0xaf0 kernel/trace/trace.c:7129
 vfs_read+0x1e4/0xb30 fs/read_write.c:572
 ksys_read+0x12a/0x250 fs/read_write.c:717
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0x830 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb1aad9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb1abca5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fb1ab015fa0 RCX: 00007fb1aad9ce59
RDX: 0000000000001000 RSI: 00002000000002c0 RDI: 0000000000000008
RBP: 00007fb1aae32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb1ab016038 R14: 00007fb1ab015fa0 R15: 00007ffec139a1b8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5ceb4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 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 0x44dc0(GFP_KERNEL|__GFP_ZERO|__GFP_RETRY_MAYFAIL|__GFP_COMP), pid 5959, tgid 5958 (syz.1.37), ts 95924498456, free_ts 95918916027
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x11a6/0x33b0 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x27c/0x2bc0 mm/page_alloc.c:5226
 __alloc_pages_noprof+0xb/0x110 mm/page_alloc.c:5260
 __alloc_pages_node_noprof include/linux/gfp.h:289 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:316 [inline]
 alloc_cpu_data+0x60/0x130 kernel/trace/ring_buffer.c:406
 ring_buffer_alloc_read_page+0x430/0x560 kernel/trace/ring_buffer.c:6801
 tracing_buffers_read+0x603/0xaf0 kernel/trace/trace.c:7110
 vfs_read+0x1e4/0xb30 fs/read_write.c:572
 ksys_read+0x12a/0x250 fs/read_write.c:717
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0x830 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5946 tgid 5945 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 __free_frozen_pages+0x747/0x1040 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+0x12a/0x410 kernel/fork.c:1178
 mmput+0x67/0x80 kernel/fork.c:1201
 exit_mm kernel/exit.c:582 [inline]
 do_exit+0x8b2/0x2af0 kernel/exit.c:964
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1119
 get_signal+0x20ff/0x2210 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+0x8b/0x4f0 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:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x6f2/0x830 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88805ceb4f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805ceb4f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805ceb5000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88805ceb5080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88805ceb5100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/25 15:47 upstream e7ae89a0c97c c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: use-after-free Write in ring_buffer_read_page
* Struck through repros no longer work on HEAD.