Bug 2492399 (CVE-2026-53067)

Summary: CVE-2026-53067 kernel: PCI: endpoint: pci-ep-msi: Fix error unwind and prevent double alloc
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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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 Linux kernel's PCI (Peripheral Component Interconnect) endpoint Message Signaled Interrupts (MSI) doorbell allocation. When MSI allocation fails, the system may attempt to free already freed memory, leading to a double-free vulnerability. This issue can result in memory corruption or a denial of service (DoS) condition, making the system unstable or unresponsive. Additionally, improper handling of already allocated doorbells could lead to memory leaks or overwriting existing allocations.
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Description OSIDB Bzimport 2026-06-24 18:09:59 UTC 
In the Linux kernel, the following vulnerability has been resolved:

PCI: endpoint: pci-ep-msi: Fix error unwind and prevent double alloc

pci_epf_alloc_doorbell() stores the allocated doorbell message array in
epf->db_msg/epf->num_db before requesting MSI vectors. If MSI allocation
fails, the array is freed but the EPF state may still point to freed
memory.

Clear epf->db_msg and epf->num_db on the MSI allocation failure path so
that later cleanup cannot double-free the array and callers can retry
allocation.

Also return -EBUSY when doorbells have already been allocated to prevent
leaking or overwriting an existing allocation.
Comment 1 Mauro Matteo Cascella 2026-06-26 14:38:25 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062403-CVE-2026-53067-ec86@gregkh/T