KASAN: slab-use-after-free Read in __ext4_iget

Status: upstream: reported on 2025/08/15 02:29
Reported-by: syzbot+a08013e80f8d0b18d42b@syzkaller.appspotmail.com
First crash: 359d, last: 30d
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in __ext4_iget fs reiserfs 19 278 922d 1159d 0/29 auto-obsoleted due to no activity on 2024/04/09 13:42
linux-6.1 KASAN: use-after-free Read in __ext4_iget 19 2 696d 738d 0/3 auto-obsoleted due to no activity on 2024/12/21 07:26
android-54 KASAN: use-after-free Read in __ext4_iget (3) 19 syz, C 58 441d 514d 0/2 upstream: reported C repro on 2025/03/13 17:21
linux-5.15 KASAN: use-after-free Read in __ext4_iget 19 58 2d13h 921d 0/3 upstream: reported on 2024/01/31 03:06
linux-6.1 KASAN: slab-out-of-bounds Read in __ext4_iget (2) 19 47 51d 554d 0/3 upstream: reported on 2025/02/01 20:39
android-5-15 KASAN: use-after-free Read in __ext4_iget origin:lts 19 syz, C 728 4d21h 495d 0/2 upstream: reported C repro on 2025/04/01 19:00
linux-5.15 KASAN: slab-out-of-bounds Read in __ext4_iget 19 6 1027d 1070d 0/3 auto-obsoleted due to no activity on 2024/01/25 22:09
android-54 KASAN: use-after-free Read in __ext4_iget 19 13 899d 1106d 0/2 auto-obsoleted due to no activity on 2024/05/22 19:07
android-5-10 KASAN: use-after-free Read in __ext4_iget 19 syz, C 562 2d16h 519d 0/2 upstream: reported C repro on 2025/03/08 14:28
android-54 KASAN: use-after-free Read in __ext4_iget (2) 19 4 781d 799d 0/2 auto-obsoleted due to no activity on 2024/09/17 10:19
linux-6.1 KASAN: slab-out-of-bounds Read in __ext4_iget 19 14 861d 1117d 0/3 auto-obsoleted due to no activity on 2024/07/09 19:10

Sample crash report:
loop3: detected capacity change from 0 to 2048
==================================================================
BUG: KASAN: slab-use-after-free in check_igot_inode fs/ext4/inode.c:-1 [inline]
BUG: KASAN: slab-use-after-free in __ext4_iget+0x2c0/0x3f40 fs/ext4/inode.c:4850
Read of size 8 at addr ffff88805cff99b0 by task syz.3.13610/4483

CPU: 0 PID: 4483 Comm: syz.3.13610 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 check_igot_inode fs/ext4/inode.c:-1 [inline]
 __ext4_iget+0x2c0/0x3f40 fs/ext4/inode.c:4850
 __ext4_fill_super fs/ext4/super.c:5517 [inline]
 ext4_fill_super+0x503a/0x67b0 fs/ext4/super.c:5744
 get_tree_bdev+0x3f3/0x520 fs/super.c:1591
 vfs_get_tree+0x8c/0x280 fs/super.c:1764
 do_new_mount+0x24b/0xa40 fs/namespace.c:3386
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2e7/0x3d0 fs/namespace.c:3912
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f54bb39e0ca
Code: 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007f54bc273e58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f54bc273ee0 RCX: 00007f54bb39e0ca
RDX: 0000200000000780 RSI: 0000200000000480 RDI: 00007f54bc273ea0
RBP: 0000200000000780 R08: 00007f54bc273ee0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000480
R13: 00007f54bc273ea0 R14: 00000000000007a1 R15: 0000200000000540
 </TASK>

Allocated by task 20761:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4b0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3495 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc_lru+0x111/0x2d0 mm/slub.c:3526
 alloc_inode_sb include/linux/fs.h:2946 [inline]
 reiserfs_alloc_inode+0x2a/0xc0 fs/reiserfs/super.c:642
 alloc_inode fs/inode.c:261 [inline]
 new_inode_pseudo+0x63/0x1d0 fs/inode.c:1049
 new_inode+0x22/0x1b0 fs/inode.c:1075
 reiserfs_mkdir+0x1d6/0x920 fs/reiserfs/namei.c:813
 xattr_mkdir fs/reiserfs/xattr.c:77 [inline]
 create_privroot fs/reiserfs/xattr.c:891 [inline]
 reiserfs_xattr_init+0x33c/0x6a0 fs/reiserfs/xattr.c:1007
 reiserfs_fill_super+0x1ff2/0x23b0 fs/reiserfs/super.c:2175
 mount_bdev+0x221/0x2d0 fs/super.c:1643
 legacy_get_tree+0xea/0x180 fs/fs_context.c:662
 vfs_get_tree+0x8c/0x280 fs/super.c:1764
 do_new_mount+0x24b/0xa40 fs/namespace.c:3386
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2e7/0x3d0 fs/namespace.c:3912
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
 __call_rcu_common kernel/rcu/tree.c:2721 [inline]
 call_rcu+0x153/0x950 kernel/rcu/tree.c:2837
 destroy_inode fs/inode.c:316 [inline]
 evict+0x835/0x8d0 fs/inode.c:720
 dispose_list fs/inode.c:738 [inline]
 evict_inodes+0x606/0x6a0 fs/inode.c:792
 generic_shutdown_super+0x97/0x2b0 fs/super.c:672
 kill_block_super+0x44/0x90 fs/super.c:1660
 deactivate_locked_super+0x97/0x100 fs/super.c:481
 cleanup_mnt+0x43b/0x4d0 fs/namespace.c:1259
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Second to last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
 __call_rcu_common kernel/rcu/tree.c:2721 [inline]
 call_rcu+0x153/0x950 kernel/rcu/tree.c:2837
 destroy_inode fs/inode.c:316 [inline]
 evict+0x835/0x8d0 fs/inode.c:720
 reiserfs_fill_super+0x1479/0x23b0 fs/reiserfs/super.c:2078
 mount_bdev+0x221/0x2d0 fs/super.c:1643
 legacy_get_tree+0xea/0x180 fs/fs_context.c:662
 vfs_get_tree+0x8c/0x280 fs/super.c:1764
 do_new_mount+0x24b/0xa40 fs/namespace.c:3386
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2e7/0x3d0 fs/namespace.c:3912
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88805cff93e0
 which belongs to the cache reiser_inode_cache of size 1568
The buggy address is located 1488 bytes inside of
 freed 1568-byte region [ffff88805cff93e0, ffff88805cff9a00)

The buggy address belongs to the physical page:
page:ffffea000173fe00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88805cffc240 pfn:0x5cff8
head:ffffea000173fe00 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88805b8e2b01
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff8881426b6a00 dead000000000122 0000000000000000
raw: ffff88805cffc240 000000008013000a 00000001ffffffff ffff88805b8e2b01
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Reclaimable, gfp_mask 0x1d20d0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL|__GFP_RECLAIMABLE), pid 8407, tgid 8406 (syz.2.1092), ts 260829224556, free_ts 184586671094
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1581
 prep_new_page mm/page_alloc.c:1588 [inline]
 get_page_from_freelist+0x1951/0x19e0 mm/page_alloc.c:3220
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4500
 alloc_slab_page+0x5d/0x160 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:2081
 ___slab_alloc+0xc5d/0x12f0 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc_lru+0x1aa/0x2d0 mm/slub.c:3526
 alloc_inode_sb include/linux/fs.h:2946 [inline]
 reiserfs_alloc_inode+0x2a/0xc0 fs/reiserfs/super.c:642
 alloc_inode fs/inode.c:261 [inline]
 iget5_locked+0xa2/0x260 fs/inode.c:1314
 reiserfs_fill_super+0x11d7/0x23b0 fs/reiserfs/super.c:2053
 mount_bdev+0x221/0x2d0 fs/super.c:1643
 legacy_get_tree+0xea/0x180 fs/fs_context.c:662
 vfs_get_tree+0x8c/0x280 fs/super.c:1764
 do_new_mount+0x24b/0xa40 fs/namespace.c:3386
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2e7/0x3d0 fs/namespace.c:3912
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1181 [inline]
 free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2365
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2458
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x319/0x400 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4b0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3495 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc+0x11a/0x2d0 mm/slub.c:3519
 getname_flags+0xbb/0x500 fs/namei.c:140
 do_sys_openat2+0xda/0x1d0 fs/open.c:1415
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1447
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff88805cff9880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805cff9900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88805cff9980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff88805cff9a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805cff9a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (27):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/11 00:07 linux-6.6.y 924b4a879cbb b754d2d8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/05/18 21:39 linux-6.6.y eac8889a3a1c 9f74d399 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/05/11 19:25 linux-6.6.y 3b9f64db0496 d168f260 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/05/11 06:44 linux-6.6.y 3b9f64db0496 845acb1c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/05/07 12:13 linux-6.6.y 258cf62a6dfd cbf9e0fc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/05/06 11:16 linux-6.6.y 258cf62a6dfd 1dddfd3d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/04/27 09:01 linux-6.6.y 9760bf04666d 0f700595 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/04/25 00:23 linux-6.6.y 9760bf04666d 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/04/13 22:40 linux-6.6.y 8cee53b8eaeb 1a086e7c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/03/07 00:30 linux-6.6.y 4fc00fe35d46 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/01/26 10:17 linux-6.6.y cbb31f77b879 a4c52dd6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/01/23 09:45 linux-6.6.y cbb31f77b879 e2b1b6e6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/01/17 16:33 linux-6.6.y cbb31f77b879 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2025/10/20 14:05 linux-6.6.y f231f248323d d422939c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2025/10/07 22:19 linux-6.6.y e617101e5626 7e2882b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2025/08/21 13:39 linux-6.6.y bb9c90ab9c5a 3e79b825 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2025/08/19 13:22 linux-6.6.y bb9c90ab9c5a 254a27c1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2025/08/15 02:28 linux-6.6.y 3a8ababb8b6a 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ext4_iget
2026/07/10 00:35 linux-6.6.y da47cbc25466 4167ee25 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in __ext4_iget
2026/06/22 17:01 linux-6.6.y d1cfde2d5d15 5a630be6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in __ext4_iget
2026/05/07 12:28 linux-6.6.y 258cf62a6dfd cbf9e0fc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in __ext4_iget
2026/05/04 03:17 linux-6.6.y 258cf62a6dfd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in __ext4_iget
2026/04/02 10:03 linux-6.6.y c09fbcd31ae6 91bc79b0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in __ext4_iget
2026/03/21 03:52 linux-6.6.y 4fc00fe35d46 5b92003d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in __ext4_iget
2026/02/13 05:09 linux-6.6.y 1b4ef5214f17 6a673c50 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in __ext4_iget
2026/01/23 21:58 linux-6.6.y cbb31f77b879 4f25b9b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in __ext4_iget
2025/10/17 21:49 linux-6.6.y 0bbbd97a442d 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in __ext4_iget
* Struck through repros no longer work on HEAD.