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BUG: KASAN: slab-out-of-bounds in af_alg_pull_tsgl+0x1c6/0x740
Read of size 8 at addr ffff8881711c46e0 by task syz.2.624/9041

CPU: 1 UID: 0 PID: 9041 Comm: syz.2.624 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_report+0xba/0x230
 kasan_report+0x117/0x150
 af_alg_pull_tsgl+0x1c6/0x740
 skcipher_recvmsg+0x5df/0x1140
 sock_recvmsg+0x172/0x1b0
 ____sys_recvmsg+0x1e6/0x4a0
 ___sys_recvmsg+0x215/0x590
 do_recvmmsg+0x334/0x800
 __x64_sys_recvmmsg+0x198/0x250
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f007fd9c819
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:00007f007dff6028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f0080015fa0 RCX: 00007f007fd9c819
RDX: 0000000000000001 RSI: 0000200000003f00 RDI: 0000000000000004
RBP: 00007f007fe32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0080016038 R14: 00007f0080015fa0 R15: 00007ffdf8d20598
 </TASK>

Allocated by task 9041:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_noprof+0x35c/0x760
 sock_kmalloc+0xd6/0x160
 skcipher_recvmsg+0x54d/0x1140
 sock_recvmsg+0x172/0x1b0
 ____sys_recvmsg+0x1e6/0x4a0
 ___sys_recvmsg+0x215/0x590
 do_recvmmsg+0x334/0x800
 __x64_sys_recvmmsg+0x198/0x250
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8881711c46c0
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes to the right of
 allocated 32-byte region [ffff8881711c46c0, ffff8881711c46e0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8881711c4840 pfn:0x1711c4
flags: 0x57ff00000000200(workingset|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000200 ffff888100041780 ffff8881604004c8 ffffea0005c54810
raw: ffff8881711c4840 0000000800400035 00000000f5000000 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 0xd2800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4877, tgid 4877 (kworker/u9:3), ts 21504047725, free_ts 21503374838
 post_alloc_hook+0x231/0x280
 get_page_from_freelist+0x24dc/0x2580
 __alloc_frozen_pages_noprof+0x18d/0x380
 allocate_slab+0x77/0x660
 refill_objects+0x331/0x3c0
 __pcs_replace_empty_main+0x2e6/0x730
 __kmalloc_cache_noprof+0x392/0x660
 kmem_cache_free+0x15b/0x630
 release_task+0xfeb/0x16f0
 do_exit+0x1674/0x23c0
 call_usermodehelper_exec_async+0x357/0x360
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30
page last free pid 53 tgid 53 stack trace:
 __free_frozen_pages+0xc2b/0xdb0
 __kasan_populate_vmalloc+0x1b2/0x1d0
 alloc_vmap_area+0xd73/0x14b0
 __get_vm_area_node+0x1f8/0x300
 __vmalloc_node_range_noprof+0x372/0x1730
 __vmalloc_node_noprof+0xc2/0x100
 dup_task_struct+0x275/0x9a0
 copy_process+0x508/0x3cd0
 kernel_clone+0x248/0x8e0
 user_mode_thread+0x110/0x180
 call_usermodehelper_exec_work+0x5c/0x230
 process_scheduled_works+0xb6e/0x18c0
 worker_thread+0xa53/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30

Memory state around the buggy address:
 ffff8881711c4580: 00 00 00 fc fc fc fc fc fa fb fb fb fc fc fc fc
 ffff8881711c4600: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
>ffff8881711c4680: fa fb fb fb fc fc fc fc 00 00 00 00 fc fc fc fc
                                                       ^
 ffff8881711c4700: fa fb fb fb fc fc fc fc 00 00 00 00 fc fc fc fc
 ffff8881711c4780: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
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