[v5.15] KASAN: use-after-free Read in ext4_search_dir

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 471e639e59d1 Linux 5.15.117
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13c6ceef280000
kernel config: https://syzkaller.appspot.com/x/.config?x=6390289bcc1381aa
dashboard link: https://syzkaller.appspot.com/bug?extid=49e1219c6cb561ada5b9
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17e11b5f280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12b429cf280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/145b7f137d72/disk-471e639e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b5bd2fcb945c/vmlinux-471e639e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/794584032e0f/bzImage-471e639e.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/6fe96e865054/mount_0.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/fc352d3f5313/mount_7.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+49e121...@syzkaller.appspotmail.com

EXT4-fs (loop0): 1 truncate cleaned up
EXT4-fs (loop0): mounted filesystem without journal. Opts: jqfmt=vfsold,resgid=0x000000000000ee00,bh,noload,data_err=ignore,usrjquota=,,errors=continue. Quota mode: none.
==================================================================
BUG: KASAN: use-after-free in ext4_search_dir+0xee/0x1b0 fs/ext4/namei.c:1539
Read of size 1 at addr ffff888070d8f3ed by task syz-executor168/3509

CPU: 0 PID: 3509 Comm: syz-executor168 Not tainted 5.15.117-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
print_address_description+0x63/0x3b0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:434 [inline]
kasan_report+0x16b/0x1c0 mm/kasan/report.c:451
ext4_search_dir+0xee/0x1b0 fs/ext4/namei.c:1539
ext4_find_inline_entry+0x4b6/0x5e0 fs/ext4/inline.c:1700
__ext4_find_entry+0x2b0/0x1b20 fs/ext4/namei.c:1612
ext4_lookup_entry fs/ext4/namei.c:1767 [inline]
ext4_lookup+0x3c6/0xaa0 fs/ext4/namei.c:1835
lookup_open fs/namei.c:3370 [inline]
open_last_lookups fs/namei.c:3462 [inline]
path_openat+0x110e/0x2f20 fs/namei.c:3669
do_filp_open+0x21c/0x460 fs/namei.c:3699
do_sys_openat2+0x13b/0x500 fs/open.c:1211
do_sys_open fs/open.c:1227 [inline]
__do_sys_open fs/open.c:1235 [inline]
__se_sys_open fs/open.c:1231 [inline]
__x64_sys_open+0x221/0x270 fs/open.c:1231
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f5fc9455cf9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff59a4b7e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 000000000000dd5c RCX: 00007f5fc9455cf9
RDX: 0000000000000000 RSI: 0000000000141042 RDI: 0000000020000100
RBP: 0000000000000000 R08: 000000000001f210 R09: 00000000200012c0
R10: 00007f5fb8c48000 R11: 0000000000000246 R12: 00007fff59a4b81c
R13: 00007fff59a4b850 R14: 00007fff59a4b830 R15: 0000000000000004
</TASK>

The buggy address belongs to the page:
page:ffffea0001c363c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x70d8f
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001c36408 ffffea0001c36388 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x1100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 3507, ts 56768897628, free_ts 56796369712
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x322a/0x33c0 mm/page_alloc.c:4159
__alloc_pages+0x272/0x700 mm/page_alloc.c:5421
alloc_pages_vma+0x39a/0x800 mm/mempolicy.c:2146
do_anonymous_page mm/memory.c:3795 [inline]
handle_pte_fault mm/memory.c:4606 [inline]
__handle_mm_fault mm/memory.c:4743 [inline]
handle_mm_fault+0x2f49/0x5950 mm/memory.c:4841
do_user_addr_fault arch/x86/mm/fault.c:1397 [inline]
handle_page_fault arch/x86/mm/fault.c:1485 [inline]
exc_page_fault+0x271/0x740 arch/x86/mm/fault.c:1541
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:568
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1340 [inline]
free_pcp_prepare mm/page_alloc.c:1391 [inline]
free_unref_page_prepare+0xc34/0xcf0 mm/page_alloc.c:3317
free_unref_page_list+0x1f7/0x8e0 mm/page_alloc.c:3433
release_pages+0x1bb9/0x1f40 mm/swap.c:963
tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:240 [inline]
tlb_flush_mmu mm/mmu_gather.c:247 [inline]
tlb_finish_mmu+0x177/0x320 mm/mmu_gather.c:338
unmap_region+0x304/0x350 mm/mmap.c:2668
__do_munmap+0x12db/0x1740 mm/mmap.c:2899
__vm_munmap+0x134/0x230 mm/mmap.c:2922
__do_sys_munmap mm/mmap.c:2948 [inline]
__se_sys_munmap mm/mmap.c:2944 [inline]
__x64_sys_munmap+0x67/0x70 mm/mmap.c:2944
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
ffff888070d8f280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888070d8f300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888070d8f380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888070d8f400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888070d8f480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


---
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[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ca87e77a2ef8 Linux 6.1.34
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14ea69bb280000
kernel config: https://syzkaller.appspot.com/x/.config?x=c188e92022a334b
dashboard link: https://syzkaller.appspot.com/bug?extid=2003a2bf24a18682dbf1

compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15640337280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1105b0f3280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f48d514c343c/disk-ca87e77a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/563336f1f216/vmlinux-ca87e77a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2254afa3642b/bzImage-ca87e77a.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/797691dcc259/mount_0.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/e321a37436b8/mount_7.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+2003a2...@syzkaller.appspotmail.com

EXT4-fs: Ignoring removed bh option
EXT4-fs (loop0): mounting ext3 file system using the ext4 subsystem

EXT4-fs (loop0): 1 truncate cleaned up

EXT4-fs (loop0): mounted filesystem without journal. Quota mode: none.

==================================================================
BUG: KASAN: use-after-free in ext4_search_dir+0xee/0x1b0 fs/ext4/namei.c:1539

Read of size 1 at addr ffff8880707743ed by task syz-executor361/3543

CPU: 0 PID: 3543 Comm: syz-executor361 Not tainted 6.1.34-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
<TASK>
__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
ext4_search_dir+0xee/0x1b0 fs/ext4/namei.c:1539
ext4_find_inline_entry+0x4b6/0x5e0 fs/ext4/inline.c:1722

__ext4_find_entry+0x2b0/0x1b20 fs/ext4/namei.c:1612
ext4_lookup_entry fs/ext4/namei.c:1767 [inline]

ext4_lookup+0x176/0x740 fs/ext4/namei.c:1835
lookup_open fs/namei.c:3391 [inline]
open_last_lookups fs/namei.c:3481 [inline]
path_openat+0x10fb/0x2e60 fs/namei.c:3711
do_filp_open+0x230/0x480 fs/namei.c:3741
do_sys_openat2+0x13b/0x500 fs/open.c:1318
do_sys_open fs/open.c:1334 [inline]
__do_sys_open fs/open.c:1342 [inline]
__se_sys_open fs/open.c:1338 [inline]
__x64_sys_open+0x221/0x270 fs/open.c:1338

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80

entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f32c086f2d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 14 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff59504138 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007fff59504178 RCX: 00007f32c086f2d9

RDX: 0000000000000000 RSI: 0000000000141042 RDI: 0000000020000100

RBP: 0000000000000000 R08: 000000000001f210 R09: 0000000000000000
R10: 00007f32b0061000 R11: 0000000000000246 R12: 00007fff59504170
R13: 0000000000000000 R14: 431bde82d7b634db R15: 0000000000000000
</TASK>

The buggy address belongs to the physical page:
page:ffffea0001c1dd00 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x70774
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001c1dd48 ffffea0001c1dc88 0000000000000000

raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed

page last allocated via order 0, migratetype Movable, gfp_mask 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO), pid 3543, tgid 3543 (syz-executor361), ts 66021111866, free_ts 66049240361
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x18d/0x1b0 mm/page_alloc.c:2533
prep_new_page mm/page_alloc.c:2540 [inline]
get_page_from_freelist+0x32ed/0x3480 mm/page_alloc.c:4292
__alloc_pages+0x28d/0x770 mm/page_alloc.c:5559
__folio_alloc+0xf/0x30 mm/page_alloc.c:5591
vma_alloc_folio+0x486/0x990 mm/mempolicy.c:2241
alloc_page_vma include/linux/gfp.h:284 [inline]
do_anonymous_page mm/memory.c:4123 [inline]
handle_pte_fault mm/memory.c:4962 [inline]
__handle_mm_fault mm/memory.c:5106 [inline]
handle_mm_fault+0x2e85/0x5330 mm/memory.c:5227
do_user_addr_fault arch/x86/mm/fault.c:1428 [inline]
handle_page_fault arch/x86/mm/fault.c:1519 [inline]
exc_page_fault+0x58d/0x790 arch/x86/mm/fault.c:1575
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570

page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]

free_pages_prepare mm/page_alloc.c:1460 [inline]
free_pcp_prepare mm/page_alloc.c:1510 [inline]
free_unref_page_prepare+0xf63/0x1120 mm/page_alloc.c:3388
free_unref_page_list+0x107/0x810 mm/page_alloc.c:3530
release_pages+0x2836/0x2b40 mm/swap.c:1055
tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
tlb_flush_mmu+0xfc/0x210 mm/mmu_gather.c:261
tlb_finish_mmu+0xce/0x1f0 mm/mmu_gather.c:361
unmap_region+0x29f/0x2f0 mm/mmap.c:2229
do_mas_align_munmap+0xe98/0x15e0 mm/mmap.c:2482
do_mas_munmap+0x246/0x2b0 mm/mmap.c:2540
__vm_munmap+0x268/0x370 mm/mmap.c:2817
__do_sys_munmap mm/mmap.c:2842 [inline]
__se_sys_munmap mm/mmap.c:2839 [inline]
__x64_sys_munmap+0x5c/0x70 mm/mmap.c:2839

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80

entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:

ffff888070774280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888070774300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888070774380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888070774400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888070774480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff