Buffer I/O error on dev loop0, logical block 3245768, async page read ================================================================== BUG: KASAN: use-after-free in sysv_new_block+0x788/0x960 fs/sysv/balloc.c:113 Read of size 4 at addr ffff888053f3c0c8 by task syz.0.73/4584 CPU: 1 PID: 4584 Comm: syz.0.73 Not tainted 6.1.119-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 print_address_description mm/kasan/report.c:284 [inline] print_report+0x15f/0x4f0 mm/kasan/report.c:395 kasan_report+0x136/0x160 mm/kasan/report.c:495 sysv_new_block+0x788/0x960 fs/sysv/balloc.c:113 alloc_branch fs/sysv/itree.c:134 [inline] get_block+0x2e7/0x1790 fs/sysv/itree.c:253 __block_write_begin_int+0x544/0x1a30 fs/buffer.c:1991 __block_write_begin fs/buffer.c:2041 [inline] block_write_begin+0x98/0x1f0 fs/buffer.c:2102 sysv_write_begin+0x2d/0x60 fs/sysv/itree.c:487 page_symlink+0x2c1/0x4e0 fs/namei.c:5218 sysv_symlink+0xcb/0x180 fs/sysv/namei.c:86 vfs_symlink+0x247/0x3d0 fs/namei.c:4471 do_symlinkat+0x21e/0x390 fs/namei.c:4500 __do_sys_symlink fs/namei.c:4522 [inline] __se_sys_symlink fs/namei.c:4520 [inline] __x64_sys_symlink+0x7a/0x90 fs/namei.c:4520 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f2746d80849 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f2747b90058 EFLAGS: 00000246 ORIG_RAX: 0000000000000058 RAX: ffffffffffffffda RBX: 00007f2746f45fa0 RCX: 00007f2746d80849 RDX: 0000000000000000 RSI: 00000000200059c0 RDI: 0000000020002840 RBP: 00007f2746df3986 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f2746f45fa0 R15: 00007ffc86d73328 The buggy address belongs to the physical page: page:ffffea00014fcf00 refcount:2 mapcount:1 mapping:ffff888056c3eeb8 index:0x9d5 pfn:0x53f3c memcg:ffff8880778d2000 aops:shmem_aops ino:41e dentry name:"dev/zero" flags: 0xfff80000080016(referenced|uptodate|lru|swapbacked|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff80000080016 ffffea00014fcec8 ffffea00014fcf48 ffff888056c3eeb8 raw: 00000000000009d5 0000000000000000 0000000200000000 ffff8880778d2000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 4585, tgid 4581 (syz.4.71), ts 102836523453, free_ts 101206870421 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x18d/0x1b0 mm/page_alloc.c:2517 prep_new_page mm/page_alloc.c:2524 [inline] get_page_from_freelist+0x3731/0x38d0 mm/page_alloc.c:4313 __alloc_pages+0x28d/0x770 mm/page_alloc.c:5590 __folio_alloc+0xf/0x30 mm/page_alloc.c:5622 vma_alloc_folio+0x486/0x990 mm/mempolicy.c:2243 shmem_alloc_folio mm/shmem.c:1589 [inline] shmem_alloc_and_acct_folio+0x5a8/0xd50 mm/shmem.c:1613 shmem_get_folio_gfp+0x13f0/0x3470 mm/shmem.c:1941 shmem_fault+0x235/0x9c0 mm/shmem.c:2156 __do_fault+0x136/0x4f0 mm/memory.c:4278 do_read_fault mm/memory.c:4629 [inline] do_fault mm/memory.c:4758 [inline] handle_pte_fault mm/memory.c:5029 [inline] __handle_mm_fault mm/memory.c:5171 [inline] handle_mm_fault+0x3410/0x5340 mm/memory.c:5292 faultin_page mm/gup.c:1009 [inline] __get_user_pages+0x4f3/0x1190 mm/gup.c:1233 populate_vma_page_range+0x217/0x2b0 mm/gup.c:1590 __mm_populate+0x275/0x440 mm/gup.c:1704 mm_populate include/linux/mm.h:2801 [inline] vm_mmap_pgoff+0x22b/0x2d0 mm/util.c:525 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1444 [inline] free_pcp_prepare mm/page_alloc.c:1494 [inline] free_unref_page_prepare+0xf63/0x1120 mm/page_alloc.c:3369 free_unref_page_list+0x663/0x900 mm/page_alloc.c:3510 release_pages+0x2836/0x2b40 mm/swap.c:1055 __pagevec_release+0x80/0xf0 mm/swap.c:1075 pagevec_release include/linux/pagevec.h:71 [inline] folio_batch_release include/linux/pagevec.h:135 [inline] shmem_undo_range+0x865/0x2390 mm/shmem.c:946 shmem_truncate_range mm/shmem.c:1062 [inline] shmem_evict_inode+0x265/0xa60 mm/shmem.c:1171 evict+0x529/0x930 fs/inode.c:701 __dentry_kill+0x436/0x650 fs/dcache.c:611 dentry_kill+0xbb/0x290 dput+0xfb/0x1d0 fs/dcache.c:918 __fput+0x62e/0x8d0 fs/file_table.c:328 task_work_run+0x246/0x300 kernel/task_work.c:203 exit_task_work include/linux/task_work.h:39 [inline] do_exit+0xa73/0x26a0 kernel/exit.c:871 do_group_exit+0x202/0x2b0 kernel/exit.c:1021 get_signal+0x16f7/0x17d0 kernel/signal.c:2871 arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:871 Memory state around the buggy address: ffff888053f3bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888053f3c000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888053f3c080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ^ ffff888053f3c100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888053f3c180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================