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KASAN: use-after-free Read in hpfs_get_ea

Status: upstream: reported C repro on 2025/07/26 19:47
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+1ded3afdecabdd33273d@syzkaller.appspotmail.com
First crash: 28d, last: 11d
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2025/07/28 upstream (ToT) 038d61fd6422 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
upstream KASAN: use-after-free Read in hpfs_get_ea fs 19 C error 31 5d06h 37d 0/29 upstream: reported C repro on 2025/07/17 19:14
linux-6.6 KASAN: use-after-free Read in hpfs_get_ea origin:upstream 19 C 3 27d 27d 0/2 upstream: reported C repro on 2025/07/27 17:30
linux-6.1 KASAN: use-after-free Read in hpfs_get_ea origin:upstream 19 C 7 6d19h 27d 0/3 upstream: reported C repro on 2025/07/27 17:28
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2025/08/12 00:12 13m retest repro linux-5.15.y report log
2025/08/12 00:12 12m retest repro linux-5.15.y report log

Sample crash report:
hpfs: You really don't want any checks? You are crazy...
hpfs: hpfs_map_sector(): read error
hpfs: code page support is disabled
==================================================================
BUG: KASAN: use-after-free in strcmp+0xc0/0xf4 lib/string.c:400
Read of size 1 at addr ffff0000e876d706 by task syz.0.16/4269

CPU: 0 PID: 4269 Comm: syz.0.16 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call trace:
 dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 print_address_description+0x78/0x30c mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xec/0x15c mm/kasan/report.c:451
 __asan_report_load1_noabort+0x44/0x50 mm/kasan/report_generic.c:306
 strcmp+0xc0/0xf4 lib/string.c:400
 hpfs_get_ea+0xfc/0x958 fs/hpfs/ea.c:139
 hpfs_read_inode+0x15c/0xcac fs/hpfs/inode.c:63
 hpfs_fill_super+0xe64/0x1800 fs/hpfs/super.c:712
 mount_bdev+0x264/0x358 fs/super.c:1400
 hpfs_mount+0x44/0x58 fs/hpfs/super.c:758
 legacy_get_tree+0xd4/0x16c fs/fs_context.c:611
 vfs_get_tree+0x90/0x274 fs/super.c:1530
 do_new_mount+0x228/0x810 fs/namespace.c:3014
 path_mount+0x5b4/0x1000 fs/namespace.c:3344
 do_mount fs/namespace.c:3357 [inline]
 __do_sys_mount fs/namespace.c:3565 [inline]
 __se_sys_mount fs/namespace.c:3542 [inline]
 __arm64_sys_mount+0x514/0x5e4 fs/namespace.c:3542
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

The buggy address belongs to the page:
page:00000000792ea48e refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x12876d
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 fffffc0003a1db88 fffffc0003a1db08 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000e876d600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000e876d680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff0000e876d700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff0000e876d780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000e876d800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
hpfs: hpfs_map_sector(): read error
hpfs: hpfs_map_sector(): read error
hpfs: hpfs_map_sector(): read error
hpfs: hpfs_map_sector(): read error
hpfs: hpfs_map_4sectors(): unaligned read
hpfs: hpfs_map_4sectors(): unaligned read
hpfs: filesystem error: unable to find root dir

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/26 20:44 linux-5.15.y c79648372d02 fb8f743d .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 KASAN: use-after-free Read in hpfs_get_ea
2025/07/26 20:02 linux-5.15.y c79648372d02 fb8f743d .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 KASAN: use-after-free Read in hpfs_get_ea
2025/07/28 09:09 linux-5.15.y c79648372d02 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 KASAN: use-after-free Read in hpfs_get_ea
2025/07/27 21:38 linux-5.15.y c79648372d02 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 KASAN: use-after-free Read in hpfs_get_ea
2025/07/26 20:00 linux-5.15.y c79648372d02 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 KASAN: use-after-free Read in hpfs_get_ea
2025/07/26 19:57 linux-5.15.y c79648372d02 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 KASAN: use-after-free Read in hpfs_get_ea
2025/07/26 19:55 linux-5.15.y c79648372d02 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 KASAN: use-after-free Read in hpfs_get_ea
2025/07/26 19:46 linux-5.15.y c79648372d02 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 KASAN: use-after-free Read in hpfs_get_ea
* Struck through repros no longer work on HEAD.