CVE-2021-47508

See a problem?
Please try reporting it to the source first.
Source
https://cve.org/CVERecord?id=CVE-2021-47508
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-47508.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2021-47508
Downstream
Related
Published
2024-05-24T15:15:11Z
Modified
2026-03-13T05:20:46Z
Severity
  • 5.5 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
[none]
Details

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_iomap_begin+0x415/0x970 [btrfs] [<00000000fb8a74b8>] iomap_iter+0x161/0x1e0 [<0000000071dff6ff>] __iomap_dio_rw+0x1df/0x700 [<000000002567ba53>] iomap_dio_rw+0x5/0x20 [<0000000072e555f8>] btrfs_file_write_iter+0x290/0x530 [btrfs] [<000000005eb3d845>] new_sync_write+0x106/0x180 [<000000003fb505bf>] vfs_write+0x24d/0x2f0 [<000000009bb57d37>] __x64_sys_pwrite64+0x69/0xa0 [<000000003eba3fdf>] do_syscall_64+0x43/0x90

In case brtfs_qgroup_reserve_data() or btrfs_delalloc_reserve_metadata() fail the allocated extent_changeset will not be freed.

So in btrfs_check_data_free_space() and btrfs_delalloc_reserve_space() free the allocated extent_changeset to get rid of the allocated memory.

The issue currently only happens in the direct IO write path, but only after 65b3c08606e5 ("btrfs: fix ENOSPC failure when attempting direct IO write into NOCOW range"), and also at defrag_one_locked_target(). Every other place is always calling extent_changeset_free() even if its call to btrfs_delalloc_reserve_space() or btrfs_check_data_free_space() has failed.

References

Affected packages

Git /

Affected ranges

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-47508.json"
unresolved_ranges 
[
    {
        "events":  [
            {
                "introduced":  "0"
            },
            {
                "fixed":  "5.15.8"
            }
        ]
    },
    {
        "events":  [
            {
                "introduced":  "0"
            },
            {
                "last_affected":  "5.16-rc1"
            }
        ]
    },
    {
        "events":  [
            {
                "introduced":  "0"
            },
            {
                "last_affected":  "5.16-rc2"
            }
        ]
    },
    {
        "events":  [
            {
                "introduced":  "0"
            },
            {
                "last_affected":  "5.16-rc3"
            }
        ]
    },
    {
        "events":  [
            {
                "introduced":  "0"
            },
            {
                "last_affected":  "5.16-rc4"
            }
        ]
    }
]