CVE-2021-47508

/// Technical description

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

btrfs: free exchange changeset on failures

Fstests runs on my VMs have show several kmemleak reports like the following.

unreferenced object 0xffff88811ae59080 (size 64):

comm "xfs_io", pid 12124, jiffies 4294987392 (age 6.368s)

hex dump (first 32 bytes):

00 c0 1c 00 00 00 00 00 ff cf 1c 00 00 00 00 00 ................

90 97 e5 1a 81 88 ff ff 90 97 e5 1a 81 88 ff ff ................

backtrace:

[<00000000ac0176d2>] ulist_add_merge+0x60/0x150 [btrfs]

[<0000000076e9f312>] set_state_bits+0x86/0xc0 [btrfs]

[<0000000014fe73d6>] set_extent_bit+0x270/0x690 [btrfs]

[<000000004f675208>] set_record_extent_bits+0x19/0x20 [btrfs]

[<00000000b96137b1>] qgroup_reserve_data+0x274/0x310 [btrfs]

[<0000000057e9dcbb>] btrfs_check_data_free_space+0x5c/0xa0 [btrfs]

[<0000000019c4511d>] btrfs_delalloc_reserve_space+0x1b/0xa0 [btrfs]

[<000000006d37e007>] btrfs_dio_i

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References