CVE-2024-50222: iov_iter: fix copy_page_from_iter_atomic() if KMAP_LOCAL_FORCE_MAP

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-11-09 · updated 2026-08-04

Description

In the Linux kernel, the following vulnerability has been resolved: iov_iter: fix copy_page_from_iter_atomic() if KMAP_LOCAL_FORCE_MAP generic/077 on x86_32 CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP=y with highmem, on huge=always tmpfs, issues a warning and then hangs (interruptibly): WARNING: CPU: 5 PID: 3517 at mm/highmem.c:622 kunmap_local_indexed+0x62/0xc9 CPU: 5 UID: 0 PID: 3517 Comm: cp Not tainted 6.12.0-rc4 #2 ... copy_page_from_iter_atomic+0xa6/0x5ec generic_perform_write+0xf6/0x1b4 shmem_file_write_iter+0x54/0x67 Fix copy_page_from_iter_atomic() by limiting it in that case (include/linux/skbuff.h skb_frag_must_loop() does similar). But going forward, perhaps CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP is too surprising, has outlived its usefulness, and should just be removed?

Affected products

Linux kernel: from 6.6 before 6.6.60; from 6.7 before 6.11.7; 6.12-rc1, 6.12-rc2, 6.12-rc3, 6.12-rc4, 6.12-rc5 — fixed in 6.11.7, 6.6.60

How to fix

Upgrade to a fixed version: Linux kernel 6.11.7, 6.6.60. Check the vendor advisory for mitigations.

References

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