CVE-2025-40043

In the Linux kernel, the following vulnerability has been resolved: net: nfc: nci: Add parameter validation for packet data Syzbot reported an uninitialized value bug in nci_init_req, which was introduced by commit 5aca7966d2a7 ("Merge tag 'perf-tools-fixes-for-v6.17-2025-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools"). This bug arises due to very limited and poor input validation that was done at nic_valid_size(). This validation only validates the skb->len (directly reflects size provided at the userspace interface) with the length provided in the buffer itself (interpreted as NCI_HEADER). This leads to the processing of memory content at the address assuming the correct layout per what opcode requires there. This leads to the accesses to buffer of `skb_buff->data` which is not assigned anything yet. Following the same silent drop of packets of invalid sizes at `nic_valid_size()`, add validation of the data in the respective handlers and return error values in case of failure. Release the skb if error values are returned from handlers in `nci_nft_packet` and effectively do a silent drop Possible TODO: because we silently drop the packets, the call to `nci_request` will be waiting for completion of request and will face timeouts. These timeouts can get excessively logged in the dmesg. A proper handling of them may require to export `nci_request_cancel` (or propagate error handling from the nft packets handlers).

• https://git.kernel.org/stable/c/0ba68bea1e356f466ad29449938bea12f5f3711f
• https://git.kernel.org/stable/c/74837bca0748763a77f77db47a0bdbe63b347628
• https://git.kernel.org/stable/c/8fcc7315a10a84264e55bb65ede10f0af20a983f
• https://git.kernel.org/stable/c/9c328f54741bd5465ca1dc717c84c04242fac2e1
• https://git.kernel.org/stable/c/bfdda0123dde406dbff62e7e9136037e97998a15
• https://git.kernel.org/stable/c/c395d1e548cc68e84584ffa2e3ca9796a78bf7b9

Published

Oct 28, 2025

Last Modified

Jun 17, 2026

Status

Deferred