KASAN: use-after-free Read in hpfs_get_ea

Status: upstream: reported C repro on 2025/07/27 17:30
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+91209a63bd6e8b2608e4@syzkaller.appspotmail.com
First crash: 363d, last: 12h06m
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2025/07/30 upstream (ToT) beb6c8326eb4 C [report] KASAN: use-after-free Read in hpfs_get_ea
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 KASAN: use-after-free Read in hpfs_get_ea origin:upstream 19 C 589 20h22m 364d 0/3 upstream: reported C repro on 2025/07/26 19:47
upstream KASAN: use-after-free Read in hpfs_get_ea prio:high fs 19 C error 9804 1h01m 373d 0/29 upstream: reported C repro on 2025/07/17 19:14
linux-6.1 KASAN: use-after-free Read in hpfs_get_ea origin:upstream 19 C 1177 21h36m 363d 0/3 upstream: reported C repro on 2025/07/27 17:28
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2026/03/18 03:14 4m bisect fix linux-6.6.y error job log
2025/08/31 05:47 1h46m bisect fix linux-6.6.y OK (0) job log log

Sample crash report:
hpfs: filesystem error: improperly stopped; already mounted read-only
hpfs: filesystem error: warning: spare dnodes used, try chkdsk
hpfs: You really don't want any checks? You are crazy...
hpfs: hpfs_map_sector(): read error
hpfs: code page support is disabled
hpfs: hpfs_map_sector(): read error
hpfs: hpfs_map_sector(): read error
hpfs: hpfs_map_sector(): read error
==================================================================
BUG: KASAN: use-after-free in strcmp+0x6b/0xb0 lib/string.c:288
Read of size 1 at addr ffff88806ca82002 by task syz.0.17/5945

CPU: 1 PID: 5945 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
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
 strcmp+0x6b/0xb0 lib/string.c:288
 hpfs_get_ea+0x138/0xea0 fs/hpfs/ea.c:139
 hpfs_read_inode+0x78d/0x1050 fs/hpfs/inode.c:89
 hpfs_fill_super+0x12f2/0x1f40 fs/hpfs/super.c:712
 mount_bdev+0x21c/0x2c0 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+0x24a/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: 0033:0x7f401eb9f10a
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:00007ffd76e84128 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffd76e841b0 RCX: 00007f401eb9f10a
RDX: 0000200000000080 RSI: 0000200000009ec0 RDI: 00007ffd76e84170
RBP: 0000200000000080 R08: 00007ffd76e841b0 R09: 0000000003a00041
R10: 0000000003a00041 R11: 0000000000000246 R12: 0000200000009ec0
R13: 00007ffd76e84170 R14: 0000000000009e31 R15: 0000200000000000
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0001b2a080 refcount:1 mapcount:1 mapping:0000000000000000 index:0x1d1 pfn:0x6ca82
memcg:ffff88801a67a000
anon flags: 0xfff800000a0028(uptodate|lru|mappedtodisk|swapbacked|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0x0()
raw: 00fff800000a0028 ffffea0001b29c48 ffffea0001b2a488 ffff8880779edcc1
raw: 00000000000001d1 0000000000000000 0000000100000000 ffff88801a67a000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 5438, tgid 5438 (dhcpcd), ts 122445347769, free_ts 122411644262
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582
 prep_new_page mm/page_alloc.c:1589 [inline]
 get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501
 __folio_alloc+0x10/0x20 mm/page_alloc.c:4533
 vma_alloc_folio+0x474/0x8f0 mm/mempolicy.c:2240
 wp_page_copy mm/memory.c:3094 [inline]
 do_wp_page+0x11bc/0x34d0 mm/memory.c:3469
 handle_pte_fault mm/memory.c:5063 [inline]
 __handle_mm_fault mm/memory.c:5188 [inline]
 handle_mm_fault+0x1306/0x4a50 mm/memory.c:5353
 do_user_addr_fault+0xad2/0x12d0 arch/x86/mm/fault.c:1322
 handle_page_fault arch/x86/mm/fault.c:1463 [inline]
 exc_page_fault+0x64/0x100 arch/x86/mm/fault.c:1516
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2505
 release_pages+0x208a/0x2300 mm/swap.c:1022
 tlb_batch_pages_flush mm/mmu_gather.c:99 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:294 [inline]
 tlb_flush_mmu+0x379/0x510 mm/mmu_gather.c:301
 tlb_finish_mmu+0xf4/0x220 mm/mmu_gather.c:425
 unmap_region+0x311/0x370 mm/mmap.c:2349
 do_vmi_align_munmap+0x1057/0x16a0 mm/mmap.c:2592
 do_vmi_munmap+0x252/0x2d0 mm/mmap.c:2660
 __vm_munmap+0x19e/0x3c0 mm/mmap.c:2961
 __do_sys_munmap mm/mmap.c:2978 [inline]
 __se_sys_munmap mm/mmap.c:2975 [inline]
 __x64_sys_munmap+0x60/0x70 mm/mmap.c:2975
 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:
 ffff88806ca81f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806ca81f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88806ca82000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                   ^
 ffff88806ca82080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806ca82100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (427):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/26 02:47 linux-6.6.y c5596480c50e 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/07/26 02:25 linux-6.6.y c5596480c50e 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/07/26 02:02 linux-6.6.y c5596480c50e 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/03/29 18:41 linux-6.6.y c09fbcd31ae6 b5ceaad2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2025/11/10 03:57 linux-6.6.y 0a805b6ea8cd 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2025/07/27 17:53 linux-6.6.y dbcb8d8e4163 fb8f743d .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/07/26 01:31 linux-6.6.y c5596480c50e 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/07/23 19:43 linux-6.6.y da47cbc25466 71a13572 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/07/22 23:15 linux-6.6.y da47cbc25466 881ce5c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/07/22 11:00 linux-6.6.y da47cbc25466 4a865b71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/07/22 09:40 linux-6.6.y da47cbc25466 b561ce9c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/07/10 13:20 linux-6.6.y da47cbc25466 4167ee25 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/07/04 09:23 linux-6.6.y d1cfde2d5d15 fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/06/25 16:34 linux-6.6.y d1cfde2d5d15 cfa969bf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/06/22 13:05 linux-6.6.y d1cfde2d5d15 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/06/11 08:38 linux-6.6.y 924b4a879cbb b754d2d8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/06/10 06:22 linux-6.6.y 924b4a879cbb 34dab4be .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/06/03 20:03 linux-6.6.y 924b4a879cbb 234057e5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/05/25 12:11 linux-6.6.y 0a40c6fbd105 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/05/17 08:14 linux-6.6.y 4d922539ad7d de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/05/11 06:47 linux-6.6.y 3b9f64db0496 845acb1c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/05/11 06:47 linux-6.6.y 3b9f64db0496 845acb1c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/05/10 18:17 linux-6.6.y 3b9f64db0496 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/04/26 13:38 linux-6.6.y 9760bf04666d 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/04/26 12:06 linux-6.6.y 9760bf04666d 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/04/26 10:45 linux-6.6.y 9760bf04666d 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/04/25 18:43 linux-6.6.y 9760bf04666d 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/04/23 10:45 linux-6.6.y 9760bf04666d 4c3406dc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/04/23 09:25 linux-6.6.y 9760bf04666d b10da5ec .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/04/19 21:44 linux-6.6.y 9760bf04666d 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/04/12 23:59 linux-6.6.y 8cee53b8eaeb 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/04/12 23:56 linux-6.6.y 8cee53b8eaeb 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/04/11 22:52 linux-6.6.y 8cee53b8eaeb 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/04/06 23:44 linux-6.6.y 80de0a958133 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/03/31 09:19 linux-6.6.y c09fbcd31ae6 aeea1c72 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/03/31 05:14 linux-6.6.y c09fbcd31ae6 d0af506e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/03/29 18:19 linux-6.6.y c09fbcd31ae6 b5ceaad2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/02/16 02:42 linux-6.6.y 1b4ef5214f17 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/02/05 18:31 linux-6.6.y 2cf6f68313dc 4936e85c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/01/11 14:58 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/01/08 18:35 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/01/08 18:31 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/01/07 11:29 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/01/07 10:19 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/01/06 20:58 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2025/07/27 17:29 linux-6.6.y dbcb8d8e4163 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: use-after-free Read in hpfs_get_ea
2026/07/26 00:36 linux-6.6.y c5596480c50e 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in hpfs_get_ea
2026/06/01 01:36 linux-6.6.y 0a40c6fbd105 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in hpfs_get_ea
2026/05/03 01:07 linux-6.6.y 258cf62a6dfd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in hpfs_get_ea
2026/03/30 01:52 linux-6.6.y c09fbcd31ae6 b5ceaad2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in hpfs_get_ea
2026/01/09 23:52 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in hpfs_get_ea
2026/01/08 19:02 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: out-of-bounds Read in hpfs_get_ea
* Struck through repros no longer work on HEAD.