================================================================== BUG: KASAN: use-after-free in strcmp+0x9b/0xb0 lib/string.c:346 Read of size 1 at addr ffff88806c2238c4 by task syz-executor.2/9222 CPU: 1 PID: 9222 Comm: syz-executor.2 Not tainted 5.17.0-rc5-syzkaller-00041-g73878e5eb1bd #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: __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] __ia32_sys_madvise+0xa4/0x110 mm/madvise.c:1396 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c RIP: 0023:0xf6eac549 Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f58a65cc EFLAGS: 00000296 ORIG_RAX: 00000000000000db RAX: ffffffffffffffda RBX: 0000000020ffc000 RCX: 0000000000004000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 9222: 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:2313 [inline] __do_sys_prctl+0xeb5/0x12d0 kernel/sys.c:2602 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c Freed by task 9222: 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+0x126/0x160 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+0xd0/0x390 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] __ia32_sys_madvise+0xa4/0x110 mm/madvise.c:1396 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c The buggy address belongs to the object at ffff88806c2238c0 which belongs to the cache kmalloc-16 of size 16 The buggy address is located 4 bytes inside of 16-byte region [ffff88806c2238c0, ffff88806c2238d0) The buggy address belongs to the page: page:ffffea0001b088c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6c223 flags: 0x4fff00000000200(slab|node=1|zone=1|lastcpupid=0x7ff) raw: 04fff00000000200 dead000000000100 dead000000000122 ffff888010c423c0 raw: 0000000000000000 0000000080800080 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 3699, ts 228289238106, free_ts 0 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_node include/linux/gfp.h:572 [inline] alloc_slab_page mm/slub.c:1801 [inline] allocate_slab+0x80/0x3c0 mm/slub.c:1944 new_slab mm/slub.c:2004 [inline] ___slab_alloc+0xbe1/0x12b0 mm/slub.c:3018 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105 slab_alloc_node mm/slub.c:3196 [inline] __kmalloc_node+0x339/0x4a0 mm/slub.c:4468 kmalloc_node include/linux/slab.h:604 [inline] kvmalloc_node+0x3e/0x100 mm/util.c:580 xt_jumpstack_alloc net/netfilter/x_tables.c:1354 [inline] xt_replace_table+0x1a2/0x820 net/netfilter/x_tables.c:1393 xt_register_table+0x376/0x820 net/netfilter/x_tables.c:1479 ip6t_register_table+0x139/0x360 net/ipv6/netfilter/ip6_tables.c:1752 ip6table_nat_table_init+0x47/0x470 net/ipv6/netfilter/ip6table_nat.c:116 xt_find_table_lock+0x39e/0x680 net/netfilter/x_tables.c:1259 xt_request_find_table_lock+0x27/0xf0 net/netfilter/x_tables.c:1284 get_info+0x16a/0x740 net/ipv6/netfilter/ip6_tables.c:981 do_ip6t_get_ctl+0x152/0xa10 net/ipv6/netfilter/ip6_tables.c:1663 nf_getsockopt+0x72/0xd0 net/netfilter/nf_sockopt.c:116 page_owner free stack trace missing Memory state around the buggy address: ffff88806c223780: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc ffff88806c223800: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc >ffff88806c223880: fb fb fc fc fb fb fc fc fa fb fc fc 00 04 fc fc ^ ffff88806c223900: fb fb fc fc fa fb fc fc fb fb fc fc fb fb fc fc ffff88806c223980: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc ================================================================== ---------------- Code disassembly (best guess): 0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi 4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d a: 10 06 adc %al,(%rsi) c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 10: 10 07 adc %al,(%rdi) 12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi 16: 10 08 adc %cl,(%rax) 18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1c: 00 00 add %al,(%rax) 1e: 00 00 add %al,(%rax) 20: 00 51 52 add %dl,0x52(%rcx) 23: 55 push %rbp 24: 89 e5 mov %esp,%ebp 26: 0f 34 sysenter 28: cd 80 int $0x80 * 2a: 5d pop %rbp <-- trapping instruction 2b: 5a pop %rdx 2c: 59 pop %rcx 2d: c3 retq 2e: 90 nop 2f: 90 nop 30: 90 nop 31: 90 nop 32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi