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

Status: closed as invalid on 2026/06/30 21:42
Subsystems: fuse
Labels: prio:high
[Documentation on labels]
First crash: 97d, last: 81d
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ID Workflow Result Correct Bug Created Started Finished Revision Error
66027f9c-3d48-4913-88c2-50150ee1d3b7 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in fuse_dev_do_read 2026/05/17 16:20 2026/05/17 16:20 2026/05/17 17:19 de5aae85e5f28e2fa1c7deefcc24fe286abe5140 

			
				
	

	
	



			

		

	

	
	

		

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				KASAN: slab-use-after-free Read in fuse_dev_do_read (2)
					fuse
					prio:high
			
			19
			
			
			
			2
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						moderation: reported on 2026/07/23 21:01
					
				
			
			
		

	
	





			
			
			
			
		

	

	
	

		

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				2026/05/03 12:28
				
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				2026/05/03 12:28
				
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Sample crash report:

	
==================================================================
BUG: KASAN: slab-use-after-free in __list_del_entry_valid_or_report+0x18a/0x1d0 lib/list_debug.c:49
Read of size 8 at addr ffff88802fb43c88 by task syz.0.17/6092

CPU: 2 UID: 0 PID: 6092 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
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
 __list_del_entry_valid_or_report+0x18a/0x1d0 lib/list_debug.c:49
 __list_del_entry_valid include/linux/list.h:132 [inline]
 __list_del_entry include/linux/list.h:223 [inline]
 list_del_init include/linux/list.h:295 [inline]
 fuse_read_interrupt fs/fuse/dev.c:1267 [inline]
 fuse_dev_do_read+0x5fa/0x2420 fs/fuse/dev.c:1464
 fuse_dev_read+0x15e/0x1e0 fs/fuse/dev.c:1586
 io_iter_do_read io_uring/rw.c:835 [inline]
 __io_read+0x357/0x1470 io_uring/rw.c:952
 io_read+0x8d/0x1f0 io_uring/rw.c:1031
 __io_issue_sqe+0xe8/0x7a0 io_uring/io_uring.c:1387
 io_issue_sqe+0x88/0x13e0 io_uring/io_uring.c:1410
 io_queue_sqe io_uring/io_uring.c:1636 [inline]
 io_req_task_submit+0x15f/0x290 io_uring/io_uring.c:1050
 io_poll_task_func+0xa2a/0xde0 io_uring/poll.c:361
 io_handle_tw_list+0x194/0x580 io_uring/tw.c:72
 tctx_task_work_run+0x59/0x330 io_uring/tw.c:132
 tctx_task_work+0x7a/0xd0 io_uring/tw.c:150
 task_work_run+0x150/0x240 kernel/task_work.c:233
 get_signal+0x1bd/0x21e0 kernel/signal.c:2809
 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+0x86/0x4a0 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:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:328 [inline]
 do_syscall_64+0x706/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f589e99c819
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:00007f589f81e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: fffffffffffffffc RBX: 00007f589ec16090 RCX: 00007f589e99c819
RDX: 0000000000040000 RSI: 0000200000000140 RDI: ffffffffffffff9c
RBP: 00007f589ea32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000020 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f589ec16128 R14: 00007f589ec16090 R15: 00007ffc3bdf5828
 </TASK>

Allocated by task 6092:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4569 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 kmem_cache_alloc_noprof+0x241/0x6e0 mm/slub.c:4905
 fuse_request_alloc+0x22/0x200 fs/fuse/dev.c:142
 fuse_get_req+0x74a/0xfe0 fs/fuse/dev.c:225
 __fuse_simple_request+0xb5/0xf00 fs/fuse/dev.c:688
 fuse_simple_request fs/fuse/fuse_i.h:1262 [inline]
 fuse_lookup_name+0x2ad/0x760 fs/fuse/dir.c:578
 fuse_lookup+0x209/0x550 fs/fuse/dir.c:625
 fuse_atomic_open+0x2f8/0x450 fs/fuse/dir.c:944
 atomic_open+0x179/0x430 fs/namei.c:4364
 lookup_open.isra.0+0x46b/0x11b0 fs/namei.c:4477
 open_last_lookups fs/namei.c:4611 [inline]
 path_openat+0xa98/0x31a0 fs/namei.c:4855
 do_file_open+0x20e/0x430 fs/namei.c:4887
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6092:
 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+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2689 [inline]
 slab_free mm/slub.c:6246 [inline]
 kmem_cache_free+0x127/0x6c0 mm/slub.c:6373
 fuse_request_free fs/fuse/dev.c:151 [inline]
 fuse_put_request+0x1ed/0x320 fs/fuse/dev.c:287
 __fuse_simple_request+0x589/0xf00 fs/fuse/dev.c:705
 fuse_simple_request fs/fuse/fuse_i.h:1262 [inline]
 fuse_lookup_name+0x2ad/0x760 fs/fuse/dir.c:578
 fuse_lookup+0x209/0x550 fs/fuse/dir.c:625
 fuse_atomic_open+0x2f8/0x450 fs/fuse/dir.c:944
 atomic_open+0x179/0x430 fs/namei.c:4364
 lookup_open.isra.0+0x46b/0x11b0 fs/namei.c:4477
 open_last_lookups fs/namei.c:4611 [inline]
 path_openat+0xa98/0x31a0 fs/namei.c:4855
 do_file_open+0x20e/0x430 fs/namei.c:4887
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802fb43c70
 which belongs to the cache fuse_request of size 216
The buggy address is located 24 bytes inside of
 freed 216-byte region [ffff88802fb43c70, ffff88802fb43d48)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88802fb43d88 pfn:0x2fb42
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff8881012a2f00 ffff888021e81288 ffff888021e81288
raw: ffff88802fb43d88 00000008001d001b 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff8881012a2f00 ffff888021e81288 ffff888021e81288
head: ffff88802fb43d88 00000008001d001b 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6092, tgid 6090 (syz.0.17), ts 62301804631, free_ts 62171569452
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x153/0x170 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x11a6/0x33b0 mm/page_alloc.c:3938
 __alloc_frozen_pages_noprof+0x27c/0x2bc0 mm/page_alloc.c:5218
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab mm/slub.c:3467 [inline]
 new_slab+0xa6/0x6c0 mm/slub.c:3525
 refill_objects+0x277/0x420 mm/slub.c:7251
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x375/0x650 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 kmem_cache_alloc_noprof+0x480/0x6e0 mm/slub.c:4905
 fuse_request_alloc+0x22/0x200 fs/fuse/dev.c:142
 fuse_get_req+0x74a/0xfe0 fs/fuse/dev.c:225
 __fuse_simple_request+0xb5/0xf00 fs/fuse/dev.c:688
 fuse_simple_request fs/fuse/fuse_i.h:1262 [inline]
 fuse_lookup_name+0x2ad/0x760 fs/fuse/dir.c:578
 fuse_lookup+0x209/0x550 fs/fuse/dir.c:625
 fuse_atomic_open+0x2f8/0x450 fs/fuse/dir.c:944
 atomic_open+0x179/0x430 fs/namei.c:4364
 lookup_open.isra.0+0x46b/0x11b0 fs/namei.c:4477
 open_last_lookups fs/namei.c:4611 [inline]
 path_openat+0xa98/0x31a0 fs/namei.c:4855
page last free pid 5346 tgid 5346 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0x747/0x1040 mm/page_alloc.c:2935
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4569 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 kmem_cache_alloc_node_noprof+0x25a/0x6f0 mm/slub.c:4950
 __alloc_skb+0x140/0x710 net/core/skbuff.c:702
 alloc_skb include/linux/skbuff.h:1383 [inline]
 netlink_alloc_large_skb+0x69/0x150 net/netlink/af_netlink.c:1184
 netlink_sendmsg+0x680/0xda0 net/netlink/af_netlink.c:1869
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2698
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2752
 __sys_sendmsg+0x170/0x220 net/socket.c:2784
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88802fb43b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802fb43c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fa fb
>ffff88802fb43c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88802fb43d00: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc
 ffff88802fb43d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================



	

	



	Crashes (2):
		
		

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			2026/04/19 12:08
			upstream
			faeab166167f
			303e2802
			.config
			console log
			report
			syz / log
			C
			
			
				[disk image (non-bootable)]
			
				[vmlinux]
			
				[kernel image]
			
			ci-qemu-upstream
			KASAN: slab-use-after-free Read in fuse_dev_do_read
		

		
		

			2026/04/17 10:34
			upstream
			3cd8b194bf34
			de0a551d
			.config
			console log
			report
			syz / log
			C
			
			
				[disk image (non-bootable)]
			
				[vmlinux]
			
				[kernel image]
			
			ci-qemu-upstream
			KASAN: slab-use-after-free Read in fuse_dev_do_read
		

		
		


* Struck through repros no longer work on HEAD.