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How the mentioned CVE works
This vulnerability exists within the `io_uring` subsystem’s zero-copy receive (zcrx) and page pool (pp) mechanisms in the Linux kernel. The system allocates notification I/O vectors (niovs) to manage data transfers. A flaw occurs during the destruction of a page pool. A misplaced warning check incorrectly triggers when not all niovs have been returned to the zcrx pool before destruction. This indicates an underlying race condition or resource management error where a `struct io_pp_zc` can be freed while it still holds allocated niovs. The subsequent use of these dangling niov pointers leads to a use-after-free condition, potentially allowing a local attacker to corrupt kernel memory, cause a denial of service (system crash), or achieve arbitrary code execution with kernel privileges.
DailyCVE
Platform: Linux Kernel
Version: Affected versions pre-patch
Vulnerability: Use-After-Free
Severity: Critical
date: 2025-08-16
Prediction: 2025-09-06
What Undercode Say:
Check kernel version
uname -r
Search kernel logs for relevant warnings
dmesg | grep -i "io_uring|zcrx|page pool"
Example code snippet highlighting the problematic area (conceptual)
/
struct io_pp_zc {
// ... other members ...
struct io_niov niovs; // Can be left allocated on destruction
};
static void io_pp_zc_destroy(struct io_pp_zc pp) {
// Misplaced warning was here, checking for non-zero niov count
// The actual freeing of the 'pp' struct happens, leaving niovs dangling.
}
/
How Exploit:
A local attacker could exploit this by creating and manipulating `io_uring` instances with multiple page pools and specific zero-copy receive operations. By carefully timing the destruction of these resources, the attacker could trigger the use-after-free condition to execute arbitrary code in the kernel context, leading to full system compromise.
Protection from this CVE
Update the Linux kernel to a version that includes the commit resolving this issue. The patch removes the misplaced warning and ensures proper cleanup of all niovs before the page pool structure is destroyed, eliminating the use-after-free flaw.
Impact:
Kernel memory corruption, system crash (denial of service), and potential privilege escalation to root, allowing complete control of the affected system.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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