CVE-2024-47739: padata: use integer wrap around to prevent deadlock on seq_nr overflow
In the Linux kernel, the following vulnerability has been resolved:
padata: use integer wrap around to prevent deadlock on seq_nr overflow
When submitting more than 2^32 padata objects to padata_do_serial, the
current sorting implementation incorrectly sorts padata objects with
overflowed seq_nr, causing them to be placed before existing objects in
the reorder list. This leads to a deadlock in the serialization process
as padata_find_next cannot match padata->seq_nr and pd->processed
because the padata instance with overflowed seq_nr will be selected
next.
To fix this, we use an unsigned integer wrap around to correctly sort
padata objects in scenarios with integer overflow.
Security readout for executives and security teams
Plain-English summary
A Linux kernel sequencing flaw can deadlock parallel-data serialization after more than 2^32 objects are submitted. Affected systems may lose availability because processing stops, but the supplied sources show no confidentiality or integrity impact. Reaching the failure depends on sustained use of the kernel's padata subsystem.
Executive priority
Treat as a high-priority availability issue for exposed, high-throughput Linux workloads. Accelerate kernel updates where padata use is confirmed or uncertain; otherwise handle through the normal risk-based kernel patch cycle. No evidence supplied supports emergency incident response for active exploitation.
Technical view
The padata reorder logic mishandles a 32-bit seq_nr wraparound. An overflowed object can sort before outstanding objects, leaving padata_find_next unable to reconcile the next sequence number with the processed counter and deadlocking serialization. The kernel fix applies unsigned wraparound-aware ordering.
Likely exposure
Exposure requires an affected Linux kernel and a workload exercising padata_do_serial enough to exceed 2^32 submissions. Long-lived, high-throughput systems using padata are the clearest concern. The supplied affected-version data is ambiguous, so distribution-specific package status should determine exposure.
Exploitation context
The CVSS 3.1 score is 7.5 for network-reachable availability impact, but practical reachability depends on software paths that drive padata. The record is not in KEV, and the supplied sources do not establish active exploitation or a public exploit.
Researcher notes
The trigger is sequence exhaustion after more than 2^32 padata objects, not merely malformed input. Assess reachable kernel consumers, throughput, uptime, and counter lifecycle. The flattened affected-version list does not provide reliable range semantics; validate fixes through distribution advisories or commit inclusion rather than interpreting it as exact boundaries.
Mitigation direction
Apply a vendor-supported kernel update containing the referenced padata fix.
Check Linux distribution advisories for the corrected package version.
Follow vendor restart or reboot guidance after installing the kernel update.
Prioritize long-lived, high-throughput systems known to exercise padata.
Validation and detection
Inventory running kernel versions, not only installed kernel packages.
Compare each distribution package against its vendor advisory and fixed build.
Confirm the referenced fix is present when maintaining a custom kernel.
After updating, verify systems booted into the intended corrected kernel.
Monitor affected workloads for serialization stalls or unexplained availability loss.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Potential ATT&CK relevance
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