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BUG: KASAN: use-after-free in strcmp+0x9b/0xb0 lib/string.c:346
Read of size 1 at addr ffff888084b51784 by task syz-executor.4/30836

CPU: 0 PID: 30836 Comm: syz-executor.4 Not tainted 5.17.0-rc3-syzkaller-00247-g83e396641110 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255
 __kasan_report mm/kasan/report.c:442 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
 strcmp+0x9b/0xb0 lib/string.c:346
 replace_vma_anon_name mm/madvise.c:141 [inline]
 madvise_update_vma+0x4e6/0x7f0 mm/madvise.c:212
 madvise_vma_behavior+0x116/0x1910 mm/madvise.c:1043
 madvise_walk_vmas+0x1d5/0x2d0 mm/madvise.c:1207
 do_madvise mm/madvise.c:1385 [inline]
 do_madvise+0x249/0x3c0 mm/madvise.c:1343
 __do_sys_madvise mm/madvise.c:1398 [inline]
 __se_sys_madvise mm/madvise.c:1396 [inline]
 __x64_sys_madvise+0xa6/0x110 mm/madvise.c:1396
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fe244164059
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe242ad9168 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007fe244276f60 RCX: 00007fe244164059
RDX: 0000000000000000 RSI: 0000000000003000 RDI: 0000000020ffc000
RBP: 00007fe2441be08d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe2447aab1f R14: 00007fe242ad9300 R15: 0000000000022000
 </TASK>

Allocated by task 30836:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:436 [inline]
 ____kasan_kmalloc mm/kasan/common.c:515 [inline]
 ____kasan_kmalloc mm/kasan/common.c:474 [inline]
 __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524
 kmalloc include/linux/slab.h:586 [inline]
 anon_vma_name_alloc mm/madvise.c:75 [inline]
 replace_vma_anon_name mm/madvise.c:146 [inline]
 madvise_update_vma+0x546/0x7f0 mm/madvise.c:212
 madvise_vma_anon_name+0x7c/0xc0 mm/madvise.c:1236
 madvise_walk_vmas+0x1d5/0x2d0 mm/madvise.c:1207
 madvise_set_anon_name+0xac/0xe0 mm/madvise.c:1269
 prctl_set_vma kernel/sys.c:2305 [inline]
 __do_sys_prctl+0xeb5/0x12d0 kernel/sys.c:2594
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 30836:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track+0x21/0x30 mm/kasan/common.c:45
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free+0x130/0x160 mm/kasan/common.c:328
 kasan_slab_free include/linux/kasan.h:236 [inline]
 slab_free_hook mm/slub.c:1728 [inline]
 slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1754
 slab_free mm/slub.c:3509 [inline]
 kfree+0xcb/0x280 mm/slub.c:4562
 vma_anon_name_free mm/madvise.c:88 [inline]
 kref_put include/linux/kref.h:65 [inline]
 free_vma_anon_name mm/madvise.c:125 [inline]
 free_vma_anon_name+0xeb/0x110 mm/madvise.c:116
 vm_area_free+0x11/0x30 kernel/fork.c:376
 __vma_adjust+0x836/0x24a0 mm/mmap.c:962
 vma_merge+0x3fa/0xeb0 mm/mmap.c:1237
 madvise_update_vma+0x1b6/0x7f0 mm/madvise.c:180
 madvise_vma_behavior+0x116/0x1910 mm/madvise.c:1043
 madvise_walk_vmas+0x1d5/0x2d0 mm/madvise.c:1207
 do_madvise mm/madvise.c:1385 [inline]
 do_madvise+0x249/0x3c0 mm/madvise.c:1343
 __do_sys_madvise mm/madvise.c:1398 [inline]
 __se_sys_madvise mm/madvise.c:1396 [inline]
 __x64_sys_madvise+0xa6/0x110 mm/madvise.c:1396
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff888084b51780
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 4 bytes inside of
 8-byte region [ffff888084b51780, ffff888084b51788)
The buggy address belongs to the page:
page:ffffea000212d440 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x84b51
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0000dca1c0 dead000000000002 ffff888010c41280
raw: 0000000000000000 0000000080660066 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 3631, ts 2792368758902, free_ts 2792368668422
 prep_new_page mm/page_alloc.c:2434 [inline]
 get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389
 alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271
 alloc_slab_page mm/slub.c:1799 [inline]
 allocate_slab mm/slub.c:1944 [inline]
 new_slab+0x28a/0x3b0 mm/slub.c:2004
 ___slab_alloc+0x87c/0xe90 mm/slub.c:3018
 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105
 slab_alloc_node mm/slub.c:3196 [inline]
 __kmalloc_node+0x2cb/0x390 mm/slub.c:4468
 kmalloc_node include/linux/slab.h:604 [inline]
 __vmalloc_area_node mm/vmalloc.c:2948 [inline]
 __vmalloc_node_range+0x444/0x1060 mm/vmalloc.c:3107
 __vmalloc_node mm/vmalloc.c:3157 [inline]
 vzalloc+0x67/0x80 mm/vmalloc.c:3227
 do_ip6t_get_ctl+0x60f/0xa10 net/ipv6/netfilter/ip6_tables.c:817
 nf_getsockopt+0x72/0xd0 net/netfilter/nf_sockopt.c:116
 ipv6_getsockopt+0x1be/0x270 net/ipv6/ipv6_sockglue.c:1502
 tcp_getsockopt+0x86/0xd0 net/ipv4/tcp.c:4293
 __sys_getsockopt+0x21f/0x5f0 net/socket.c:2224
 __do_sys_getsockopt net/socket.c:2239 [inline]
 __se_sys_getsockopt net/socket.c:2236 [inline]
 __x64_sys_getsockopt+0xba/0x150 net/socket.c:2236
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1352 [inline]
 free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404
 free_unref_page_prepare mm/page_alloc.c:3325 [inline]
 free_unref_page+0x19/0x690 mm/page_alloc.c:3404
 __vunmap+0x798/0xc50 mm/vmalloc.c:2635
 __vfree+0x3c/0xd0 mm/vmalloc.c:2683
 vfree+0x5a/0x90 mm/vmalloc.c:2714
 copy_entries_to_user net/ipv6/netfilter/ip6_tables.c:884 [inline]
 get_entries net/ipv6/netfilter/ip6_tables.c:1041 [inline]
 do_ip6t_get_ctl+0x82f/0xa10 net/ipv6/netfilter/ip6_tables.c:1672
 nf_getsockopt+0x72/0xd0 net/netfilter/nf_sockopt.c:116
 ipv6_getsockopt+0x1be/0x270 net/ipv6/ipv6_sockglue.c:1502
 tcp_getsockopt+0x86/0xd0 net/ipv4/tcp.c:4293
 __sys_getsockopt+0x21f/0x5f0 net/socket.c:2224
 __do_sys_getsockopt net/socket.c:2239 [inline]
 __se_sys_getsockopt net/socket.c:2236 [inline]
 __x64_sys_getsockopt+0xba/0x150 net/socket.c:2236
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Memory state around the buggy address:
 ffff888084b51680: fc fc fb fc fc fc fc fa fc fc fc fc 00 fc fc fc
 ffff888084b51700: fc fb fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc
>ffff888084b51780: fa fc fc fc fc fa fc fc fc fc 00 fc fc fc fc 00
                   ^
 ffff888084b51800: fc fc fc fc fb fc fc fc fc fb fc fc fc fc fb fc
 ffff888084b51880: fc fc fc fb fc fc fc fc fa fc fc fc fc fb fc fc
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