Bug 2492443 (CVE-2026-52989)

Summary: CVE-2026-52989 kernel: nvmet-tcp: propagate nvmet_tcp_build_pdu_iovec() errors to its callers
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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. The `nvmet_tcp_build_pdu_iovec()` function fails to propagate errors when detecting out-of-bounds PDU lengths or offsets. This can lead to uninitialized memory being used by subsequent operations, such as reading incoming network data into an uninitialized iterator. A remote attacker could potentially exploit this memory corruption to cause a denial of service or achieve arbitrary code execution.
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Description OSIDB Bzimport 2026-06-24 18:12:22 UTC 
In the Linux kernel, the following vulnerability has been resolved:

nvmet-tcp: propagate nvmet_tcp_build_pdu_iovec() errors to its callers

Currently, when nvmet_tcp_build_pdu_iovec() detects an out-of-bounds
PDU length or offset, it triggers nvmet_tcp_fatal_error(cmd->queue)
and returns early. However, because the function returns void, the
callers are entirely unaware that a fatal error has occurred and
that the cmd->recv_msg.msg_iter was left uninitialized.

Callers such as nvmet_tcp_handle_h2c_data_pdu() proceed to blindly
overwrite the queue state with queue->rcv_state = NVMET_TCP_RECV_DATA
Consequently, the socket receiving loop may attempt to read incoming
network data into the uninitialized iterator.

Fix this by shifting the error handling responsibility to the callers.
Comment 1 Mauro Matteo Cascella 2026-06-25 09:18:36 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062444-CVE-2026-52989-beb8@gregkh/T