CVE-2026-93186

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux583fa5e71caeb79e04e477e9837e2f7fa53b71e4 < f5d2bbf0300f46307948864fbb97bce5097f4fe2affected
LinuxLinux583fa5e71caeb79e04e477e9837e2f7fa53b71e4 < 31d4841eca7c4b75751ca96d24339e19303337f2affected
LinuxLinux583fa5e71caeb79e04e477e9837e2f7fa53b71e4 < b4e11c731d6bee3b87315e055a1ca417c92dc1fcaffected
LinuxLinux583fa5e71caeb79e04e477e9837e2f7fa53b71e4 < 8a13db9f899d149c3aab24abcb668121cfda5a4faffected
LinuxLinux5.12affected
LinuxLinux0 < 5.12unaffected
LinuxLinux6.12.110 <= 6.12.*unaffected
LinuxLinux6.18.52 <= 6.18.*unaffected
LinuxLinux7.2.6 <= 7.2.*unaffected
LinuxLinux7.3-rc1 <= *unaffected

Weaknesses

References