================================================================== BUG: KASAN: use-after-free in strcmp+0x9b/0xb0 lib/string.c:346 Read of size 1 at addr ffff888018cf5f54 by task syz-executor.3/20532 CPU: 1 PID: 20532 Comm: syz-executor.3 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: __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: 0023:0xf6e9c549 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:00000000f58965cc EFLAGS: 00000296 ORIG_RAX: 00000000000000db RAX: ffffffffffffffda RBX: 0000000020ffc000 RCX: 0000000000003000 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 20532: 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_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 20532: 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+0xc87/0xeb0 mm/mmap.c:1213 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 ffff888018cf5f50 which belongs to the cache kmalloc-8 of size 8 The buggy address is located 4 bytes inside of 8-byte region [ffff888018cf5f50, ffff888018cf5f58) The buggy address belongs to the page: page:ffffea0000633d40 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888018cf50f0 pfn:0x18cf5 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 ffffea0001b6b380 dead000000000002 ffff888010c41280 raw: ffff888018cf50f0 000000008066005e 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 3639, ts 229344158080, free_ts 229343820722 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] vmalloc+0x67/0x80 mm/vmalloc.c:3190 xt_compat_init_offsets+0xdf/0x220 net/netfilter/x_tables.c:733 compat_table_info+0xb7/0x510 net/ipv4/netfilter/arp_tables.c:779 get_info+0x290/0x750 net/ipv4/netfilter/arp_tables.c:816 do_arpt_get_ctl+0x474/0x8f0 net/ipv4/netfilter/arp_tables.c:1444 nf_getsockopt+0x72/0xd0 net/netfilter/nf_sockopt.c:116 ip_getsockopt net/ipv4/ip_sockglue.c:1786 [inline] ip_getsockopt+0x164/0x1c0 net/ipv4/ip_sockglue.c:1765 tcp_getsockopt+0x86/0xd0 net/ipv4/tcp.c:4293 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 xt_compat_flush_offsets+0x8b/0x160 net/netfilter/x_tables.c:691 compat_do_ebt_get_ctl+0x46f/0xae0 net/bridge/netfilter/ebtables.c:2437 do_ebt_get_ctl+0x2b0/0x790 net/bridge/netfilter/ebtables.c:2459 nf_getsockopt+0x72/0xd0 net/netfilter/nf_sockopt.c:116 ip_getsockopt net/ipv4/ip_sockglue.c:1786 [inline] ip_getsockopt+0x164/0x1c0 net/ipv4/ip_sockglue.c:1765 tcp_getsockopt+0x86/0xd0 net/ipv4/tcp.c:4293 __sys_getsockopt+0x21f/0x5f0 net/socket.c:2224 __do_compat_sys_socketcall+0x513/0x660 net/compat.c:495 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 Memory state around the buggy address: ffff888018cf5e00: fc fc fb fc fc fc fc fa fc fc fc fc fa fc fc fc ffff888018cf5e80: fc fa fc fc fc fc fa fc fc fc fc fa fc fc fc fc >ffff888018cf5f00: fa fc fc fc fc fb fc fc fc fc fa fc fc fc fc fa ^ ffff888018cf5f80: fc fc fc fc fb fc fc fc fc fa fc fc fc fc fc fc ffff888018cf6000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ================================================================== ---------------- 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