R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fffa1cf52af R14: 00007f1dc9478300 R15: 0000000000022000
EXT4-fs (loop1): group descriptors corrupted!
================================================
WARNING: lock held when returning to user space!
6.18.0-rc7-next-20251128 #1 Not tainted
------------------------------------------------
syz-executor.3/5542 is leaving the kernel with locks still held!
1 lock held by syz-executor.3/5542:
#0: ffff88801c688f08 (&sb->s_type->i_mutex_key#20/1){+.+.}-{4:4}, at: start_creating_noperm+0x84/0xd0
netlink: 52 bytes leftover after parsing attributes in process `syz-executor.6'.
netlink: 52 bytes leftover after parsing attributes in process `syz-executor.6'.
netlink: 52 bytes leftover after parsing attributes in process `syz-executor.6'.
netlink: 52 bytes leftover after parsing attributes in process `syz-executor.6'.
EXT4-fs warning (device sda): verify_group_input:161: Bad blocks count 0
==================================================================
BUG: KASAN: slab-use-after-free in rwsem_down_write_slowpath+0x1522/0x1670
Read of size 4 at addr ffff888019159bf4 by task syz-executor.3/5661
CPU: 1 UID: 0 PID: 5661 Comm: syz-executor.3 Not tainted 6.18.0-rc7-next-20251128 #1 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
dump_stack_lvl+0xca/0x120
print_report+0xcb/0x610
kasan_report+0xca/0x100
rwsem_down_write_slowpath+0x1522/0x1670
down_write_nested+0x1c6/0x1f0
start_creating_noperm+0x84/0xd0
do_mq_open+0x25f/0x980
__x64_sys_mq_open+0x14f/0x1e0
do_syscall_64+0xbf/0x420
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f132ba6ab19
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1328fe0188 EFLAGS: 00000246 ORIG_RAX: 00000000000000f0
RAX: ffffffffffffffda RBX: 00007f132bb7df60 RCX: 00007f132ba6ab19
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200002c0
RBP: 00007f132bac4f6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020000340 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc505c5a6f R14: 00007f1328fe0300 R15: 0000000000022000
FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 0
Allocated by task 5535:
kasan_save_stack+0x24/0x50
kasan_save_track+0x14/0x30
__kasan_slab_alloc+0x59/0x70
CPU: 0 UID: 0 PID: 5662 Comm: syz-executor.4 Not tainted 6.18.0-rc7-next-20251128 #1 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
dump_stack_lvl+0xfa/0x120
should_fail_ex+0x4d7/0x5e0
_copy_to_user+0x32/0xd0
simple_read_from_buffer+0xe0/0x180
proc_fail_nth_read+0x18a/0x240
vfs_read+0x1eb/0xc70
ksys_read+0x121/0x240
do_syscall_64+0xbf/0x420
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1dcbeb569c
Code: ec 28 48 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 fc ff ff 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 48 89 44 24 08 e8 2f fd ff ff 48
RSP: 002b:00007f1dc9478170 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000180 RCX: 00007f1dcbeb569c
RDX: 000000000000000f RSI: 00007f1dc94781e0 RDI: 0000000000000005
RBP: 00007f1dc94781d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fffa1cf52af R14: 00007f1dc9478300 R15: 0000000000022000
kmem_cache_alloc_node_noprof+0x228/0x730
copy_process+0x460/0x7230
kernel_clone+0xea/0x7c0
__do_sys_clone+0xce/0x120
do_syscall_64+0xbf/0x420
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 97:
kasan_save_stack+0x24/0x50
kasan_save_track+0x14/0x30
kasan_save_free_info+0x3a/0x60
__kasan_slab_free+0x43/0x70
kmem_cache_free+0x2cd/0x660
rcu_core+0x73c/0x1ed0
handle_softirqs+0x1b1/0x740
__irq_exit_rcu+0xc4/0x100
irq_exit_rcu+0x9/0x20
sysvec_apic_timer_interrupt+0x70/0x80
asm_sysvec_apic_timer_interrupt+0x1a/0x20
Last potentially related work creation:
kasan_save_stack+0x24/0x50
kasan_record_aux_stack+0x89/0xa0
__call_rcu_common.constprop.0+0x70/0xad0
delayed_put_task_struct+0xde/0x230
rcu_core+0x73c/0x1ed0
handle_softirqs+0x1b1/0x740
run_ksoftirqd+0x2e/0x60
smpboot_thread_fn+0x41d/0x9d0
kthread+0x3c8/0x740
ret_from_fork+0x67a/0x7a0
ret_from_fork_asm+0x1a/0x30
Second to last potentially related work creation:
kasan_save_stack+0x24/0x50
kasan_record_aux_stack+0x89/0xa0
__call_rcu_common.constprop.0+0x70/0xad0
put_task_struct_rcu_user+0x75/0xc0
__schedule+0x1003/0x46a0
__cond_resched+0x4c/0x80
__mutex_lock+0xc5/0x2090
sched_mm_cid_exit+0x9a/0x450
do_exit+0x2db/0x2950
do_group_exit+0xd3/0x2a0
__x64_sys_exit_group+0x3e/0x50
x64_sys_call+0x18d6/0x18e0
do_syscall_64+0xbf/0x420
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888019159bc0
which belongs to the cache task_struct of size 6848
The buggy address is located 52 bytes inside of
freed 6848-byte region [ffff888019159bc0, ffff88801915b680)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x19158
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88800ca517c1
anon flags: 0x100000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0100000000000040 ffff88800944c640 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000040004 00000000f5000000 ffff88800ca517c1
head: 0100000000000040 ffff88800944c640 0000000000000000 dead000000000001
head: 0000000000000000 0000000000040004 00000000f5000000 ffff88800ca517c1
head: 0100000000000003 ffffea0000645601 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888019159a80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
ffff888019159b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888019159b80: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
^
ffff888019159c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888019159c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================