CVE-2024-50222 Information

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?

Reference

https://git.kernel.org/stable/c/4f7ffa83fa79dd52efbaef366c850aaaae06a469 https://git.kernel.org/stable/c/3a303409f271dfe0987b8f79595138340497a32d https://git.kernel.org/stable/c/c749d9b7ebbc5716af7a95f7768634b30d9446ec