Bug 2516750 (CVE-2026-74386)

Summary: CVE-2026-74386 kernel: nvmet-tcp: fix page fragment cache leak in error path
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the nvmet-tcp component of the Linux kernel. A remote attacker could repeatedly open and close connections, causing a page fragment cache leak. This vulnerability occurs when a connection is closed during the allocation process, leading to memory not being properly released. Over time, this repeated memory leak could lead to memory exhaustion, resulting in a Denial of Service (DoS) for the affected system.
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Description OSIDB Bzimport 2026-08-15 06:31:35 UTC 
In the Linux kernel, the following vulnerability has been resolved:

nvmet-tcp: fix page fragment cache leak in error path

In nvmet_tcp_alloc_queue(), when a connection is closed during the
allocation process (e.g., nvmet_tcp_set_queue_sock() returns -ENOTCONN),
the error handling jumps to out_destroy_sq and then to out_ida_remove
without draining the page fragment cache.

Although nvmet_tcp_free_cmd() is called in some error paths to release
individual page fragments, the underlying page cache reference held by
queue->pf_cache is never released. The first allocation using pf_cache
is the call to nvmet_tcp_alloc_cmd() for queue->connect, which happens
after ida_alloc() returns successfully. This results in a page leak each
time a connection fails during allocation, which could lead to memory
exhaustion over time if connections are repeatedly opened and closed.

Fix this by calling page_frag_cache_drain() before freeing the queue
structure in the out_ida_remove label.
Comment 1 Keith Grant 2026-08-20 20:00:55 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081506-CVE-2026-74386-9fc4@gregkh/T