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KASAN: use-after-free Read in ext4_xattr_list_entries

Status: upstream: reported C repro on 2026/01/18 01:47
Reported-by: syzbot+20a9a768711714797c43@syzkaller.appspotmail.com
First crash: 65d, last: 40d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/03/22 upstream (ToT) 113ae7b4decc C Failed due to an error; will retry later
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in ext4_xattr_list_entries ext4 19 4 73d 164d 0/29 moderation: reported on 2025/10/10 18:16

Sample crash report:
loop0: detected capacity change from 0 to 2048
EXT4-fs (loop0): mounted filesystem without journal. Quota mode: none.
==================================================================
BUG: KASAN: use-after-free in ext4_xattr_list_entries+0x278/0x334 fs/ext4/xattr.c:670
Read of size 4 at addr ffff0000eb560044 by task syz.0.17/4469

CPU: 0 PID: 4469 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
Call trace:
 dump_backtrace+0x1c0/0x1ec arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 __asan_report_load4_noabort+0x2c/0x38 mm/kasan/report_generic.c:350
 ext4_xattr_list_entries+0x278/0x334 fs/ext4/xattr.c:670
 ext4_xattr_ibody_list fs/ext4/xattr.c:740 [inline]
 ext4_listxattr+0x1a8/0x4e8 fs/ext4/xattr.c:765
 vfs_listxattr fs/xattr.c:457 [inline]
 listxattr+0x29c/0x3cc fs/xattr.c:804
 path_listxattr+0xe0/0x1b8 fs/xattr.c:828
 __do_sys_listxattr fs/xattr.c:840 [inline]
 __se_sys_listxattr fs/xattr.c:837 [inline]
 __arm64_sys_listxattr+0x80/0x94 fs/xattr.c:837
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 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:585

The buggy address belongs to the physical page:
page:00000000ce41c8e4 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x12b560
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 fffffc0003ad5848 fffffc0003b27bc8 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000eb55ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff0000eb55ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff0000eb560000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff0000eb560080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000eb560100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/18 07:27 linux-6.1.y cd9b81672742 20d37d28 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/10 06:41 linux-6.1.y 0182cb5b74ee 4ab09a02 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/10 06:41 linux-6.1.y 0182cb5b74ee 4ab09a02 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/12 03:25 linux-6.1.y 8ce36b2849ef 76a109e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/12 03:23 linux-6.1.y 8ce36b2849ef 76a109e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/11 08:09 linux-6.1.y 0182cb5b74ee 441e25b7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/11 03:54 linux-6.1.y 0182cb5b74ee 441e25b7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/11 02:55 linux-6.1.y 0182cb5b74ee 441e25b7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/11 02:55 linux-6.1.y 0182cb5b74ee 441e25b7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/10 16:07 linux-6.1.y 0182cb5b74ee 91d776d3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/10 14:56 linux-6.1.y 0182cb5b74ee 91d776d3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/10 03:52 linux-6.1.y 0182cb5b74ee 4ab09a02 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/01/18 01:47 linux-6.1.y cd9b81672742 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/01/18 01:46 linux-6.1.y cd9b81672742 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in ext4_xattr_list_entries
2026/02/10 14:56 linux-6.1.y 0182cb5b74ee 91d776d3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: slab-out-of-bounds Read in ext4_xattr_list_entries
* Struck through repros no longer work on HEAD.