================================================================== BUG: KASAN: use-after-free in strcmp+0x9b/0xb0 lib/string.c:346 Read of size 1 at addr ffff8880231637c4 by task syz-executor159/3587 CPU: 1 PID: 3587 Comm: syz-executor159 Not tainted 5.17.0-rc2-next-20220204-syzkaller #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+0xa5/0x3e0 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+0x116/0x19d0 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: 0033:0x7f60caa93ff9 Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff7d85f3e8 EFLAGS: 00000246 ORIG_RAX: 000000000000001c RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f60caa93ff9 RDX: 000000000000000b RSI: 0000000000001000 RDI: 0000000020ffc000 RBP: 00007f60caa57fe0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000020000000 R11: 0000000000000246 R12: 00007f60caa58070 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 3587: 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 3587: 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+0x166/0x1a0 mm/kasan/common.c:328 kasan_slab_free include/linux/kasan.h:226 [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+0xce/0x2d0 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:377 __vma_adjust+0x836/0x24a0 mm/mmap.c:962 vma_merge+0x860/0xeb0 mm/mmap.c:1217 madvise_update_vma+0x1b6/0x7f0 mm/madvise.c:180 madvise_vma_behavior+0x116/0x19d0 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 ffff8880231637c0 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 4 bytes inside of 32-byte region [ffff8880231637c0, ffff8880231637e0) The buggy address belongs to the page: page:ffffea00008c58c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x23163 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 dead000000000100 dead000000000122 ffff888010c41500 raw: 0000000000000000 0000000080400040 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, ts 17707481459, free_ts 17668236203 prep_new_page mm/page_alloc.c:2489 [inline] get_page_from_freelist+0x13ea/0x31d0 mm/page_alloc.c:4219 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5435 alloc_pages+0x1aa/0x310 mm/mempolicy.c:2268 alloc_slab_page mm/slub.c:1799 [inline] allocate_slab mm/slub.c:1944 [inline] new_slab+0x295/0x400 mm/slub.c:2004 ___slab_alloc+0x7ed/0xe00 mm/slub.c:3018 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105 slab_alloc_node mm/slub.c:3196 [inline] slab_alloc mm/slub.c:3238 [inline] kmem_cache_alloc_trace+0x289/0x2c0 mm/slub.c:3255 kmalloc include/linux/slab.h:581 [inline] kzalloc include/linux/slab.h:715 [inline] proc_init_fs_context+0x47/0x420 fs/proc/root.c:251 alloc_fs_context+0x582/0xa00 fs/fs_context.c:290 vfs_kern_mount.part.0+0x24/0x170 fs/namespace.c:1036 vfs_kern_mount fs/namespace.c:1033 [inline] kern_mount+0x4f/0xc0 fs/namespace.c:4393 process_sysctl_arg+0x38e/0x470 fs/proc/proc_sysctl.c:1855 parse_one kernel/params.c:153 [inline] parse_args+0x46e/0x8b0 kernel/params.c:188 do_sysctl_args+0xc3/0x130 fs/proc/proc_sysctl.c:1914 kernel_init+0x6f/0x1d0 init/main.c:1530 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1356 [inline] free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1406 free_unref_page_prepare mm/page_alloc.c:3376 [inline] free_unref_page+0x19/0x6c0 mm/page_alloc.c:3455 kasan_depopulate_vmalloc_pte+0x5c/0x70 mm/kasan/shadow.c:359 apply_to_pte_range mm/memory.c:2541 [inline] apply_to_pmd_range mm/memory.c:2585 [inline] apply_to_pud_range mm/memory.c:2621 [inline] apply_to_p4d_range mm/memory.c:2657 [inline] __apply_to_page_range+0x686/0x1030 mm/memory.c:2691 kasan_release_vmalloc+0xa7/0xc0 mm/kasan/shadow.c:469 __purge_vmap_area_lazy+0x8f9/0x1c50 mm/vmalloc.c:1717 _vm_unmap_aliases.part.0+0x3f0/0x500 mm/vmalloc.c:2122 _vm_unmap_aliases mm/vmalloc.c:2096 [inline] vm_unmap_aliases+0x45/0x50 mm/vmalloc.c:2145 change_page_attr_set_clr+0x241/0x500 arch/x86/mm/pat/set_memory.c:1743 change_page_attr_set arch/x86/mm/pat/set_memory.c:1793 [inline] set_memory_nx+0xb2/0x110 arch/x86/mm/pat/set_memory.c:1941 free_init_pages+0x73/0xc0 arch/x86/mm/init.c:898 kernel_init+0x2e/0x1d0 init/main.c:1516 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Memory state around the buggy address: ffff888023163680: fb fb fb fb fc fc fc fc 00 00 03 fc fc fc fc fc ffff888023163700: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc >ffff888023163780: fb fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc ^ ffff888023163800: fb fb fb fb fc fc fc fc 00 00 01 fc fc fc fc fc ffff888023163880: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ==================================================================