linux-cve-announce - CVE-2025-37738: ext4: ignore xattrs past end

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Message-ID: <2025050132-CVE-2025-37738-deb1@gregkh>
Date: Thu,  1 May 2025 14:56:44 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-37738: ext4: ignore xattrs past end

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

ext4: ignore xattrs past end

Once inside 'ext4_xattr_inode_dec_ref_all' we should
ignore xattrs entries past the 'end' entry.

This fixes the following KASAN reported issue:

==================================================================
BUG: KASAN: slab-use-after-free in ext4_xattr_inode_dec_ref_all+0xb8c/0xe90
Read of size 4 at addr ffff888012c120c4 by task repro/2065

CPU: 1 UID: 0 PID: 2065 Comm: repro Not tainted 6.13.0-rc2+ #11
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x1fd/0x300
 ? tcp_gro_dev_warn+0x260/0x260
 ? _printk+0xc0/0x100
 ? read_lock_is_recursive+0x10/0x10
 ? irq_work_queue+0x72/0xf0
 ? __virt_addr_valid+0x17b/0x4b0
 print_address_description+0x78/0x390
 print_report+0x107/0x1f0
 ? __virt_addr_valid+0x17b/0x4b0
 ? __virt_addr_valid+0x3ff/0x4b0
 ? __phys_addr+0xb5/0x160
 ? ext4_xattr_inode_dec_ref_all+0xb8c/0xe90
 kasan_report+0xcc/0x100
 ? ext4_xattr_inode_dec_ref_all+0xb8c/0xe90
 ext4_xattr_inode_dec_ref_all+0xb8c/0xe90
 ? ext4_xattr_delete_inode+0xd30/0xd30
 ? __ext4_journal_ensure_credits+0x5f0/0x5f0
 ? __ext4_journal_ensure_credits+0x2b/0x5f0
 ? inode_update_timestamps+0x410/0x410
 ext4_xattr_delete_inode+0xb64/0xd30
 ? ext4_truncate+0xb70/0xdc0
 ? ext4_expand_extra_isize_ea+0x1d20/0x1d20
 ? __ext4_mark_inode_dirty+0x670/0x670
 ? ext4_journal_check_start+0x16f/0x240
 ? ext4_inode_is_fast_symlink+0x2f2/0x3a0
 ext4_evict_inode+0xc8c/0xff0
 ? ext4_inode_is_fast_symlink+0x3a0/0x3a0
 ? do_raw_spin_unlock+0x53/0x8a0
 ? ext4_inode_is_fast_symlink+0x3a0/0x3a0
 evict+0x4ac/0x950
 ? proc_nr_inodes+0x310/0x310
 ? trace_ext4_drop_inode+0xa2/0x220
 ? _raw_spin_unlock+0x1a/0x30
 ? iput+0x4cb/0x7e0
 do_unlinkat+0x495/0x7c0
 ? try_break_deleg+0x120/0x120
 ? 0xffffffff81000000
 ? __check_object_size+0x15a/0x210
 ? strncpy_from_user+0x13e/0x250
 ? getname_flags+0x1dc/0x530
 __x64_sys_unlinkat+0xc8/0xf0
 do_syscall_64+0x65/0x110
 entry_SYSCALL_64_after_hwframe+0x67/0x6f
RIP: 0033:0x434ffd
Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 8
RSP: 002b:00007ffc50fa7b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007ffc50fa7e18 RCX: 0000000000434ffd
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000005
RBP: 00007ffc50fa7be0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc50fa7e08 R14: 00000000004bbf30 R15: 0000000000000001
 </TASK>

The buggy address belongs to the object at ffff888012c12000
 which belongs to the cache filp of size 360
The buggy address is located 196 bytes inside of
 freed 360-byte region [ffff888012c12000, ffff888012c12168)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12c12
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x40(head|node=0|zone=0)
page_type: f5(slab)
raw: 0000000000000040 ffff888000ad7640 ffffea0000497a00 dead000000000004
raw: 0000000000000000 0000000000100010 00000001f5000000 0000000000000000
head: 0000000000000040 ffff888000ad7640 ffffea0000497a00 dead000000000004
head: 0000000000000000 0000000000100010 00000001f5000000 0000000000000000
head: 0000000000000001 ffffea00004b0481 ffffffffffffffff 0000000000000000
head: 0000000000000002 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888012c11f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888012c12000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888012c12080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888012c12100: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
 ffff888012c12180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

The Linux kernel CVE team has assigned CVE-2025-37738 to this issue.


Affected and fixed versions
===========================

	Fixed in 6.1.135 with commit cf9291a3449b04688b81e32621e88de8f4314b54
	Fixed in 6.6.88 with commit 362a90cecd36e8a5c415966d0b75b04a0270e4dd
	Fixed in 6.12.24 with commit eb59cc31b6ea076021d14b04e7faab1636b87d0e
	Fixed in 6.13.12 with commit 3bc6317033f365ce578eb6039445fb66162722fd
	Fixed in 6.14.3 with commit 836e625b03a666cf93ff5be328c8cb30336db872
	Fixed in 6.15-rc1 with commit c8e008b60492cf6fd31ef127aea6d02fd3d314cd

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-37738
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	fs/ext4/xattr.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/cf9291a3449b04688b81e32621e88de8f4314b54
	https://git.kernel.org/stable/c/362a90cecd36e8a5c415966d0b75b04a0270e4dd
	https://git.kernel.org/stable/c/eb59cc31b6ea076021d14b04e7faab1636b87d0e
	https://git.kernel.org/stable/c/3bc6317033f365ce578eb6039445fb66162722fd
	https://git.kernel.org/stable/c/836e625b03a666cf93ff5be328c8cb30336db872
	https://git.kernel.org/stable/c/c8e008b60492cf6fd31ef127aea6d02fd3d314cd