net: stmmac: Fix accessing freed irq affinity_hint

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: Fix accessing freed irq affinity_hint In stmmac_request_irq_multi_msi(), a pointer to the stack variable cpu_mask is passed to irq_set_affinity_hint(). This value is stored in irq_desc->affinity_hint, but once stmmac_request_irq_multi_msi() returns, the pointer becomes dangling. The affinity_hint is exposed via procfs with S_IRUGO permissions, allowing any unprivileged process to read it. Accessing this stale pointer can lead to: - a kernel oops or panic if the referenced memory has been released and unmapped, or - leakage of kernel data into userspace if the memory is re-used for other purposes. All platforms that use stmmac with PCI MSI (Intel, Loongson, etc) are affected.

References

• https://git.kernel.org/stable/c/2fbf67ddb8a0d0efc00d2df496a9843ec318d48b
• https://git.kernel.org/stable/c/960dab23f6d405740c537d095f90a4ee9ddd9285
• https://git.kernel.org/stable/c/442312c2a90d60c7a5197246583fa91d9e579985
• https://git.kernel.org/stable/c/e148266e104fce396ad624079a6812ac3a9982ef
• https://git.kernel.org/stable/c/9e51a6a44e2c4de780a26e8fe110d708e806a8cd
• https://git.kernel.org/stable/c/c60d101a226f18e9a8f01bb4c6ca2b47dfcb15ef