Bug 2536769 (CVE-2026-90399)

Summary: CVE-2026-90399 kernel: wifi: ath12k: fix stride mismatch in mac_phy_caps_parse()
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: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's ath12k Wi-Fi driver. This vulnerability stems from incorrect memory handling within the `mac_phy_caps_parse()` function. When processing certain data packets from firmware, specifically short Type-Length-Value (TLV) structures, the driver attempts to write more data than the allocated memory buffer can hold. This out-of-bounds write can corrupt system memory, potentially leading to system instability or a denial of service.
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Description OSIDB Bzimport 2026-09-17 19:30:51 UTC 
In the Linux kernel, the following vulnerability has been resolved:

wifi: ath12k: fix stride mismatch in mac_phy_caps_parse()

Currently, in ath12k_wmi_mac_phy_caps_parse(), kzalloc() sizes the
mac_phy_caps buffer as tot_phy_id * len, where len is clamped to
min(firmware_len, sizeof(struct ath12k_wmi_mac_phy_caps_params)). The
subsequent memcpy() destination advances by sizeof(full struct) per slot
via C pointer arithmetic, not by the clamped len. When firmware sends
short TLVs, the second and later slots are written past the end of the
allocation.

The reader in ath12k_pull_mac_phy_cap_svc_ready_ext() also indexes the
buffer with full-struct pointer arithmetic, so the allocation must match
that stride.

Fix by using kzalloc_objs(), which derives the element size from the
pointer type, making allocation size and pointer stride provably
consistent regardless of what len the firmware provides.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3
Comment 1 gkamathe 2026-09-21 09:58:04 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90399.mbox