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BUG: KASAN: slab-out-of-bounds in ext4_ext_binsearch fs/ext4/extents.c:841 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_find_extent+0xae6/0xcc0 fs/ext4/extents.c:956
Read of size 4 at addr ffff88800099fd18 by task syz.0.0/5340

CPU: 0 UID: 0 PID: 5340 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 ext4_ext_binsearch fs/ext4/extents.c:841 [inline]
 ext4_find_extent+0xae6/0xcc0 fs/ext4/extents.c:956
 ext4_ext_map_blocks+0x278/0x69c0 fs/ext4/extents.c:4208
 ext4_map_create_blocks fs/ext4/inode.c:613 [inline]
 ext4_map_blocks+0x82c/0x16f0 fs/ext4/inode.c:816
 _ext4_get_block+0x1fa/0x4c0 fs/ext4/inode.c:916
 ext4_get_block_unwritten+0x2e/0x100 fs/ext4/inode.c:949
 ext4_block_write_begin+0xb03/0x1940 fs/ext4/inode.c:1203
 ext4_write_begin+0xb3a/0x1860 fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x352/0xd30 fs/ext4/inode.c:3130
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4314
 ext4_buffered_write_iter+0xce/0x3a0 fs/ext4/file.c:299
 ext4_file_write_iter+0x292/0x1bc0 fs/ext4/file.c:-1
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5c9/0xb30 fs/read_write.c:686
 ksys_write+0x145/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9389b8f7c9
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:00007f938aad6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9389de6090 RCX: 00007f9389b8f7c9
RDX: 00000000fffffdef RSI: 00002000000000c0 RDI: 0000000000000007
RBP: 00007f9389c13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9389de6128 R14: 00007f9389de6090 R15: 00007fff799771a8
 </TASK>

Allocated by task 4734:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 unpoison_slab_object mm/kasan/common.c:339 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:365
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_lru_noprof+0x36c/0x6e0 mm/slub.c:5282
 alloc_inode+0xb8/0x1b0 fs/inode.c:348
 iget_locked+0x131/0x6a0 fs/inode.c:1470
 kernfs_get_inode+0x4f/0x780 fs/kernfs/inode.c:253
 kernfs_iop_lookup+0x1f6/0x320 fs/kernfs/dir.c:1239
 __lookup_slow+0x297/0x3d0 fs/namei.c:1858
 lookup_slow+0x53/0x70 fs/namei.c:1875
 walk_component fs/namei.c:2221 [inline]
 lookup_last fs/namei.c:2722 [inline]
 path_lookupat+0x3f5/0x8c0 fs/namei.c:2746
 filename_lookup+0x212/0x570 fs/namei.c:2775
 do_readlinkat+0xd9/0x500 fs/stat.c:576
 __do_sys_readlink fs/stat.c:613 [inline]
 __se_sys_readlink fs/stat.c:610 [inline]
 __x64_sys_readlink+0x7f/0x90 fs/stat.c:610
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88800099f740
 which belongs to the cache inode_cache of size 1144
The buggy address is located 352 bytes to the right of
 allocated 1144-byte region [ffff88800099f740, ffff88800099fbb8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x998
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0x7ff00000000040(head|node=0|zone=0|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 007ff00000000040 ffff8880304178c0 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000190019 00000000f5000000 0000000000000000
head: 007ff00000000040 ffff8880304178c0 0000000000000000 dead000000000001
head: 0000000000000000 0000000000190019 00000000f5000000 0000000000000000
head: 007ff00000000003 ffffea0000026601 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Reclaimable, gfp_mask 0xd20d0(__GFP_RECLAIMABLE|__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4734, tgid 4734 (udevadm), ts 67354414626, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x234/0x290 mm/page_alloc.c:1846
 prep_new_page mm/page_alloc.c:1854 [inline]
 get_page_from_freelist+0x24e0/0x2580 mm/page_alloc.c:3915
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab+0x86/0x3b0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xe53/0x1820 mm/slub.c:4656
 __slab_alloc+0x65/0x100 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 kmem_cache_alloc_lru_noprof+0x3fe/0x6e0 mm/slub.c:5282
 alloc_inode+0xb8/0x1b0 fs/inode.c:348
 iget_locked+0x131/0x6a0 fs/inode.c:1470
 kernfs_get_inode+0x4f/0x780 fs/kernfs/inode.c:253
 kernfs_iop_lookup+0x1f6/0x320 fs/kernfs/dir.c:1239
 __lookup_slow+0x297/0x3d0 fs/namei.c:1858
 lookup_slow+0x53/0x70 fs/namei.c:1875
 walk_component fs/namei.c:2221 [inline]
 lookup_last fs/namei.c:2722 [inline]
 path_lookupat+0x3f5/0x8c0 fs/namei.c:2746
 filename_lookup+0x212/0x570 fs/namei.c:2775
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88800099fc00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88800099fc80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88800099fd00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                            ^
 ffff88800099fd80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88800099fe00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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