================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:826 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:945 Read of size 4 at addr ffff888111ebb018 by task syz.8.934/3582 CPU: 1 PID: 3582 Comm: syz.8.934 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:77 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:435 [inline] kasan_report+0xe2/0x130 mm/kasan/report.c:452 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308 ext4_ext_binsearch fs/ext4/extents.c:826 [inline] ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:945 ext4_ext_map_blocks+0x20b/0x5dd0 fs/ext4/extents.c:4166 ext4_map_blocks+0x985/0x1bd0 fs/ext4/inode.c:674 ext4_iomap_alloc fs/ext4/inode.c:3518 [inline] ext4_iomap_begin+0x6cd/0x930 fs/ext4/inode.c:3568 iomap_apply+0x157/0x720 fs/iomap/apply.c:46 __iomap_dio_rw+0x7bb/0x1120 fs/iomap/direct-io.c:531 iomap_dio_rw+0x35/0x80 fs/iomap/direct-io.c:619 ext4_dio_write_iter fs/ext4/file.c:573 [inline] ext4_file_write_iter+0xf6e/0x1980 fs/ext4/file.c:683 do_iter_readv_writev+0x478/0x5f0 fs/read_write.c:-1 do_iter_write+0x189/0x630 fs/read_write.c:866 vfs_writev+0x2a9/0x530 fs/read_write.c:939 do_writev+0x14e/0x2c0 fs/read_write.c:982 __do_sys_writev fs/read_write.c:1055 [inline] __se_sys_writev fs/read_write.c:1052 [inline] __x64_sys_writev+0x7d/0x90 fs/read_write.c:1052 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7f78a21fa819 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f78a0c13028 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007f78a2474180 RCX: 00007f78a21fa819 RDX: 0000000000000001 RSI: 0000200000000140 RDI: 0000000000000007 RBP: 00007f78a2290c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f78a2474218 R14: 00007f78a2474180 R15: 00007fff00517898 The buggy address belongs to the page: page:ffffea000447aec0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x111ebb flags: 0x4000000000000000() raw: 4000000000000000 0000000000000000 ffffea000447aec8 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as freed page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 315, ts 103162512077, free_ts 118789343392 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook mm/page_alloc.c:2456 [inline] prep_new_page+0x179/0x180 mm/page_alloc.c:2462 get_page_from_freelist+0x223b/0x23d0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x290/0x620 mm/page_alloc.c:5384 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1813 [inline] new_slab+0x84/0x3f0 mm/slub.c:1874 new_slab_objects mm/slub.c:2632 [inline] ___slab_alloc+0x2a6/0x450 mm/slub.c:2796 __slab_alloc+0x63/0xa0 mm/slub.c:2836 slab_alloc_node mm/slub.c:2918 [inline] slab_alloc mm/slub.c:2960 [inline] __kmalloc+0x1fe/0x330 mm/slub.c:4034 __kmalloc_node include/linux/slab.h:421 [inline] kmalloc_node include/linux/slab.h:578 [inline] kvmalloc_node+0x88/0x130 mm/util.c:612 kvmalloc include/linux/mm.h:833 [inline] seq_buf_alloc fs/seq_file.c:38 [inline] seq_read_iter+0x1fc/0xd30 fs/seq_file.c:210 kernfs_fop_read_iter+0x147/0x470 fs/kernfs/file.c:241 call_read_iter include/linux/fs.h:2060 [inline] new_sync_read fs/read_write.c:415 [inline] vfs_read+0x62a/0xa60 fs/read_write.c:496 ksys_read+0x149/0x250 fs/read_write.c:634 __do_sys_read fs/read_write.c:644 [inline] __se_sys_read fs/read_write.c:642 [inline] __x64_sys_read+0x7b/0x90 fs/read_write.c:642 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb page last free stack trace: reset_page_owner include/linux/page_owner.h:28 [inline] free_pages_prepare mm/page_alloc.c:1349 [inline] __free_pages_ok+0x80b/0x830 mm/page_alloc.c:1629 free_the_page mm/page_alloc.c:5445 [inline] __free_pages+0xd8/0x3b0 mm/page_alloc.c:5454 __free_slab+0xcf/0x190 mm/slub.c:1899 free_slab mm/slub.c:1914 [inline] discard_slab mm/slub.c:1920 [inline] unfreeze_partials+0x15f/0x190 mm/slub.c:2415 put_cpu_partial+0xc1/0x180 mm/slub.c:2451 __slab_free+0x2c9/0x3a0 mm/slub.c:3100 do_slab_free mm/slub.c:3196 [inline] ___cache_free+0x10e/0x130 mm/slub.c:3215 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283 ____kasan_kmalloc mm/kasan/common.c:475 [inline] __kasan_kmalloc+0x2f/0x110 mm/kasan/common.c:518 kasan_kmalloc include/linux/kasan.h:254 [inline] __kmalloc+0x1a4/0x330 mm/slub.c:4038 kmalloc include/linux/slab.h:560 [inline] kzalloc include/linux/slab.h:667 [inline] lsm_cred_alloc security/security.c:500 [inline] security_prepare_creds+0x4e/0x140 security/security.c:1639 prepare_creds+0x3f1/0x5d0 kernel/cred.c:288 copy_creds+0xe5/0x480 kernel/cred.c:361 copy_process+0x972/0x3300 kernel/fork.c:2144 Memory state around the buggy address: ffff888111ebaf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888111ebaf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff888111ebb000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff888111ebb080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888111ebb100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== EXT4-fs error (device loop8): ext4_map_blocks:740: inode #15: block 142172007432192: comm syz.8.934: lblock 1 mapped to illegal pblock 142172007432192 (length 15)