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Linux KernelOperating system · Linux

CVE-2021-47343

MEDIUM · 5.5 CVSS v3.1 Published 2024-05-21
Fix available
A fix is available. Upgrade to 4.4.276 / 4.9.276 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: dm btree remove: assign new_root only when removal succeeds remove_raw() in dm_btree_remove() may fail due to IO read error (e.g. read the content of origin block fails during shadowing), and the value of shadow_spine::root is uninitialized, but the uninitialized value is still assign to new_root in the end of dm_btree_remove(). For dm-thin, the value of pmd->details_root or pmd->root will become an uninitialized value, so if trying to read details_info tree again out-of-bound memory may occur as showed below: general protection fault, probably for non-canonical address 0x3fdcb14c8d7520 CPU: 4 PID: 515 Comm: dmsetup Not tainted 5.13.0-rc6 Hardware name: QEMU Standard PC RIP: 0010:metadata_ll_load_ie+0x14/0x30 Call Trace: sm_metadata_count_is_more_than_one+0xb9/0xe0 dm_tm_shadow_block+0x52/0x1c0 shadow_step+0x59/0xf0 remove_raw+0xb2/0x170 dm_btree_remove+0xf4/0x1c0 dm_pool_delete_thin_device+0xc3/0x140 pool_message+0x218/0x2b0 target_message+0x251/0x290 ctl_ioctl+0x1c4/0x4d0 dm_ctl_ioctl+0xe/0x20 __x64_sys_ioctl+0x7b/0xb0 do_syscall_64+0x40/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae Fixing it by only assign new_root when removal succeeds

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:< 4.4.276>= 4.5, < 4.9.276>= 4.10, < 4.14.240>= 4.15, < 4.19.198>= 4.20, < 5.4.133>= 5.5, < 5.10.51>= 5.11, < 5.12.18>= 5.13, < 5.13.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.4.276 / 4.9.276 / 4.14.240 or later
Fixed in 4.4.2764.9.2764.14.240
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux kernel 4.4.276 / 4.9.276 / 4.14.240 / 4.19.198 or later (or any stable 5.x/6.x release)

  1. Identify the currently running Linux kernel version using 'uname -r'
  2. Determine which version branch you are on (4.4.x, 4.9.x, 4.14.x, or 4.19.x)
  3. For 4.4.x branch: upgrade to kernel version 4.4.276 or later
  4. For 4.9.x branch: upgrade to kernel version 4.9.276 or later
  5. For 4.14.x branch: upgrade to kernel version 4.14.240 or later
  6. For 4.19.x branch: upgrade to kernel version 4.19.198 or later
  7. Alternatively, upgrade to any stable kernel version >= 5.0 that contains the fix (the issue was fixed in mainline around 5.13-rc1)
  8. Reboot the system after applying the kernel update
Caveat Kernel upgrades may require system reboot and could have compatibility implications with custom kernel modules or specific hardware drivers

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-47343 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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