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CVE-2021-47508— btrfs: free exchange changeset on failures

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 btrfs 模块存在漏洞。

AI Predicted 5.5 Difficulty: Easy EPSS 0.21% · P10

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 364ecf3651e0862152c8b340d7cb3021dc0122c7< ca06c5cb1b6dbfe67655b33c02fc394d65824519 affected
364ecf3651e0862152c8b340d7cb3021dc0122c7< da5e817d9d75422eaaa05490d0b9a5e328fc1a51 affected
4.13 affected
< 4.13 unaffected
5.15.8≤ 5.15.* unaffected
5.16≤ * unaffected
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I. Basic Information for CVE-2021-47508

Vulnerability Information
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Vulnerability Title
btrfs: free exchange changeset on failures
Source: CVE Program / CVE List V5
Vulnerability 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_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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 btrfs 模块存在漏洞。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 364ecf3651e0862152c8b340d7cb3021dc0122c7 ~ ca06c5cb1b6dbfe67655b33c02fc394d65824519 -
Linux Linux 4.13 -

II. Public POCs for CVE-2021-47508

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III. Intelligence Information for CVE-2021-47508

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Other References for CVE-2021-47508 (2)

Same Patch Batch · Linux · 2024-05-24 · 72 CVEs total

CVE-2021-47544 9.8 CRITICAL tcp: fix page frag corruption on page fault
CVE-2021-47536 9.8 CRITICAL net/smc: fix wrong list_del in smc_lgr_cleanup_early
CVE-2021-47506 9.8 CRITICAL nfsd: fix use-after-free due to delegation race
CVE-2021-47520 8.8 HIGH can: pch_can: pch_can_rx_normal: fix use after free
CVE-2021-47555 7.8 HIGH net: vlan: fix underflow for the real_dev refcnt
CVE-2021-47505 7.8 HIGH aio: fix use-after-free due to missing POLLFREE handling
CVE-2021-47512 7.8 HIGH net/sched: fq_pie: prevent dismantle issue
CVE-2021-47502 7.8 HIGH ASoC: codecs: wcd934x: handle channel mappping list correctly
CVE-2021-47517 7.8 HIGH ethtool: do not perform operations on net devices being unregistered
CVE-2021-47561 7.8 HIGH i2c: virtio: disable timeout handling
CVE-2023-52880 7.8 HIGH tty: n_gsm: require CAP_NET_ADMIN to attach N_GSM0710 ldisc
CVE-2021-47551 7.8 HIGH drm/amd/amdkfd: Fix kernel panic when reset failed and been triggered again
CVE-2021-47552 7.8 HIGH blk-mq: cancel blk-mq dispatch work in both blk_cleanup_queue and disk_release()
CVE-2021-47533 7.8 HIGH drm/vc4: kms: Clear the HVS FIFO commit pointer once done
CVE-2021-47535 7.8 HIGH drm/msm/a6xx: Allocate enough space for GMU registers
CVE-2021-47500 7.8 HIGH iio: mma8452: Fix trigger reference couting
CVE-2021-47541 7.8 HIGH net/mlx4_en: Fix an use-after-free bug in mlx4_en_try_alloc_resources()
CVE-2021-47515 7.5 HIGH seg6: fix the iif in the IPv6 socket control block
CVE-2021-47559 7.5 HIGH net/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk()
CVE-2021-47570 staging: r8188eu: fix a memory leak in rtw_wx_read32()

Showing top 20 of 72 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-47508

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