CVE-2026-93186

In the Linux kernel, the following vulnerability has been resolved: cxl/mbox: Clamp mailbox output allocation to the payload size CXL_MEM_SEND_COMMAND bounds the user's in.size to the mailbox payload size but leaves out.size unbounded, then cxl_mbox_cmd_ctor() calls kvzalloc(out.size). A large out.size drives a huge allocation, above INT_MAX it WARNs and taints, and with panic_on_warn=1 it panics. The transport __cxl_pci_mbox_send_cmd() already clamps the response copy to min(out.size, payload_size, device len), so the output buffer is never written beyond payload_size. Clamp the allocation to payload_size too, matching the RAW path.

• https://git.kernel.org/stable/c/123f6d154253939ce38f0ec0b6d1ba67f870e01f
• https://git.kernel.org/stable/c/31d4841eca7c4b75751ca96d24339e19303337f2
• https://git.kernel.org/stable/c/8a13db9f899d149c3aab24abcb668121cfda5a4f
• https://git.kernel.org/stable/c/b4e11c731d6bee3b87315e055a1ca417c92dc1fc
• https://git.kernel.org/stable/c/d2d40574b9b272ade32d0d77b140d990e7547f5f
• https://git.kernel.org/stable/c/f5d2bbf0300f46307948864fbb97bce5097f4fe2