[v6.1] KASAN: slab-out-of-bounds Read in __ext4_iget

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a456e1743881 Linux 6.1.39
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17cd6434a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=5e6478d39ceccfae
dashboard link: https://syzkaller.appspot.com/bug?extid=a5b7a444d322fed7e980
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/47260b2456c0/disk-a456e174.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ac087687a80a/vmlinux-a456e174.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e2c3d9e7236f/Image-a456e174.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a5b7a4...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in __ext4_iget+0x254/0x31b4 fs/ext4/inode.c:4822
Read of size 8 at addr ffff00011279ff30 by task syz-executor.4/14838

CPU: 0 PID: 14838 Comm: syz-executor.4 Not tainted 6.1.39-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:284 [inline]
print_report+0x174/0x4c0 mm/kasan/report.c:395
kasan_report+0xd4/0x130 mm/kasan/report.c:495
__asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351
__ext4_iget+0x254/0x31b4 fs/ext4/inode.c:4822
__ext4_fill_super fs/ext4/super.c:5399 [inline]
ext4_fill_super+0x5a80/0x75d0 fs/ext4/super.c:5661
get_tree_bdev+0x360/0x54c fs/super.c:1346
ext4_get_tree+0x28/0x38 fs/ext4/super.c:5691
vfs_get_tree+0x90/0x274 fs/super.c:1553
do_new_mount+0x25c/0x8c4 fs/namespace.c:3040
path_mount+0x590/0xe58 fs/namespace.c:3370
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__arm64_sys_mount+0x45c/0x594 fs/namespace.c:3568
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

Allocated by task 14654:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4c/0x80 mm/kasan/common.c:52
kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
__kasan_slab_alloc+0x74/0x8c mm/kasan/common.c:328
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook+0x74/0x458 mm/slab.h:737
slab_alloc_node mm/slub.c:3398 [inline]
slab_alloc mm/slub.c:3406 [inline]
__kmem_cache_alloc_lru mm/slub.c:3413 [inline]
kmem_cache_alloc_lru+0x1ac/0x2f8 mm/slub.c:3429
alloc_inode_sb include/linux/fs.h:3131 [inline]
proc_alloc_inode+0x2c/0xb8 fs/proc/inode.c:67
alloc_inode fs/inode.c:259 [inline]
new_inode_pseudo+0x68/0x1d0 fs/inode.c:1018
new_inode+0x38/0x174 fs/inode.c:1046
proc_pid_make_inode+0x34/0x1b0 fs/proc/base.c:1897
proc_ns_instantiate fs/proc/namespaces.c:105 [inline]
proc_ns_dir_lookup+0x19c/0x2f8 fs/proc/namespaces.c:172
lookup_open fs/namei.c:3391 [inline]
open_last_lookups fs/namei.c:3481 [inline]
path_openat+0xd3c/0x2548 fs/namei.c:3711
do_filp_open+0x1bc/0x3cc fs/namei.c:3741
do_sys_openat2+0x128/0x3d8 fs/open.c:1318
do_sys_open fs/open.c:1334 [inline]
__do_sys_openat fs/open.c:1350 [inline]
__se_sys_openat fs/open.c:1345 [inline]
__arm64_sys_openat+0x1f0/0x240 fs/open.c:1345
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

Freed by task 15:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4c/0x80 mm/kasan/common.c:52
kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516
____kasan_slab_free+0x144/0x1c0 mm/kasan/common.c:236
__kasan_slab_free+0x18/0x28 mm/kasan/common.c:244
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1724 [inline]
slab_free_freelist_hook mm/slub.c:1750 [inline]
slab_free mm/slub.c:3661 [inline]
kmem_cache_free+0x2f0/0x588 mm/slub.c:3683
proc_free_inode+0x28/0x38 fs/proc/inode.c:83
i_callback+0x50/0x78 fs/inode.c:248
rcu_do_batch kernel/rcu/tree.c:2251 [inline]
rcu_core+0x878/0x1c10 kernel/rcu/tree.c:2511
rcu_core_si+0x10/0x1c kernel/rcu/tree.c:2528
__do_softirq+0x30c/0xea0 kernel/softirq.c:571

Last potentially related work creation:
kasan_save_stack+0x40/0x70 mm/kasan/common.c:45
__kasan_record_aux_stack+0xcc/0xe8 mm/kasan/generic.c:486
kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:496
call_rcu+0xfc/0xa40 kernel/rcu/tree.c:2799
destroy_inode fs/inode.c:314 [inline]
evict+0x5fc/0x68c fs/inode.c:679
iput_final fs/inode.c:1789 [inline]
iput+0x7c0/0x8a4 fs/inode.c:1815
dentry_unlink_inode+0x370/0x4b0 fs/dcache.c:401
__dentry_kill+0x324/0x5e4 fs/dcache.c:607
shrink_dentry_list+0x41c/0x850 fs/dcache.c:1201
shrink_dcache_parent+0xbc/0x434
d_invalidate+0x114/0x2a0 fs/dcache.c:1737
proc_invalidate_siblings_dcache+0x3b8/0x660 fs/proc/inode.c:148
proc_flush_pid+0x24/0x34 fs/proc/base.c:3409
release_task+0x137c/0x1550 kernel/exit.c:278
wait_task_zombie kernel/exit.c:1205 [inline]
wait_consider_task+0x15fc/0x2754 kernel/exit.c:1432
do_wait_thread kernel/exit.c:1495 [inline]
do_wait+0x314/0xb40 kernel/exit.c:1612
kernel_wait4+0x24c/0x3d8 kernel/exit.c:1775
__do_sys_wait4 kernel/exit.c:1803 [inline]
__se_sys_wait4 kernel/exit.c:1799 [inline]
__arm64_sys_wait4+0x11c/0x2a0 kernel/exit.c:1799
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

Second to last potentially related work creation:
kasan_save_stack+0x40/0x70 mm/kasan/common.c:45
__kasan_record_aux_stack+0xcc/0xe8 mm/kasan/generic.c:486
kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:496
call_rcu+0xfc/0xa40 kernel/rcu/tree.c:2799
destroy_inode fs/inode.c:314 [inline]
evict+0x5fc/0x68c fs/inode.c:679
iput_final fs/inode.c:1789 [inline]
iput+0x7c0/0x8a4 fs/inode.c:1815
dentry_unlink_inode+0x370/0x4b0 fs/dcache.c:401
__dentry_kill+0x324/0x5e4 fs/dcache.c:607
shrink_dentry_list+0x41c/0x850 fs/dcache.c:1201
shrink_dcache_parent+0xbc/0x434
d_invalidate+0x114/0x2a0 fs/dcache.c:1737
proc_invalidate_siblings_dcache+0x3b8/0x660 fs/proc/inode.c:148
proc_flush_pid+0x24/0x34 fs/proc/base.c:3409
release_task+0x137c/0x1550 kernel/exit.c:278
wait_task_zombie kernel/exit.c:1205 [inline]
wait_consider_task+0x15fc/0x2754 kernel/exit.c:1432
do_wait_thread kernel/exit.c:1495 [inline]
do_wait+0x314/0xb40 kernel/exit.c:1612
kernel_wait4+0x24c/0x3d8 kernel/exit.c:1775
__do_sys_wait4 kernel/exit.c:1803 [inline]
__se_sys_wait4 kernel/exit.c:1799 [inline]
__arm64_sys_wait4+0x11c/0x2a0 kernel/exit.c:1799
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

The buggy address belongs to the object at ffff00011279f590
which belongs to the cache proc_inode_cache of size 1240
The buggy address is located 1224 bytes to the right of
1240-byte region [ffff00011279f590, ffff00011279fa68)

The buggy address belongs to the physical page:
page:000000004b3eb4fd refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x152798
head:000000004b3eb4fd order:3 compound_mapcount:0 compound_pincount:0
memcg:ffff0000d0f94c01
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 fffffc0004713200 dead000000000002 ffff0000c0887380
raw: 0000000000000000 0000000000170017 00000001ffffffff ffff0000d0f94c01
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff00011279fe00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff00011279fe80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff00011279ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff00011279ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff0001127a0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
EXT4-fs (loop4): corrupt root inode, run e2fsck
EXT4-fs (loop4): mount failed


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