Merge: CVE-2025-37738: ext4: ignore xattrs past end

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/6929

JIRA: https://issues.redhat.com/browse/RHEL-94247
CVE: CVE-2025-37738

```
commit c8e008b
Author: Bhupesh <bhupesh@igalia.com>
Date:   Tue Jan 28 13:57:50 2025 +0530

    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
    ==================================================================

    Reported-by: syzbot+b244bda78289b00204ed@syzkaller.appspotmail.com
    Closes: https://syzkaller.appspot.com/bug?extid=b244bda78289b00204ed
    Suggested-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
    Signed-off-by: Bhupesh <bhupesh@igalia.com>
    Link: https://patch.msgid.link/20250128082751.124948-2-bhupesh@igalia.com
    Signed-off-by: Theodore Ts'o <tytso@mit.edu>
```

Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>

---

<small>Created 2025-05-29 11:01 UTC by backporter - [KWF FAQ](https://red.ht/kernel_workflow_doc) - [Slack #team-kernel-workflow](https://redhat-internal.slack.com/archives/C04LRUPMJQ5) - [Source](https://gitlab.com/cki-project/kernel-workflow/-/blob/main/webhook/utils/backporter.py) - [Documentation](https://gitlab.com/cki-project/kernel-workflow/-/blob/main/docs/README.backporter.md) - [Report an issue](https://issues.redhat.com/secure/CreateIssueDetails!init.jspa?pid=12334433&issuetype=1&priority=4&summary=backporter+webhook+issue&components=kernel-workflow+/+backporter)</small>

Approved-by: Brian Foster <bfoster@redhat.com>
Approved-by: Eric Sandeen <esandeen@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Augusto Caringi <acaringi@redhat.com>

Author: caringi

fs/ext4/xattr.c

@@ -1177,15 +1177,24 @@ ext4_xattr_inode_dec_ref_all(handle_t *handle, struct inode *parent,
 {
 	struct inode *ea_inode;
 	struct ext4_xattr_entry *entry;
+	struct ext4_iloc iloc;
 	bool dirty = false;
 	unsigned int ea_ino;
 	int err;
 	int credits;
+	void *end;
+
+	if (block_csum)
+		end = (void *)bh->b_data + bh->b_size;
+	else {
+		ext4_get_inode_loc(parent, &iloc);
+		end = (void *)ext4_raw_inode(&iloc) + EXT4_SB(parent->i_sb)->s_inode_size;
+	}
 
 	/* One credit for dec ref on ea_inode, one for orphan list addition, */
 	credits = 2 + extra_credits;
 
-	for (entry = first; !IS_LAST_ENTRY(entry);
+	for (entry = first; (void *)entry < end && !IS_LAST_ENTRY(entry);
 	     entry = EXT4_XATTR_NEXT(entry)) {
 		if (!entry->e_value_inum)
 			continue;