CVE-2026-80603netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read

Official description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read parse_dcc() treats data_end as an inclusive end pointer, but its only caller passes data_limit = ib_ptr + datalen, which points one past the last valid byte. The newline search loop iterates while tmp <= data_end, so when no newline is present, *tmp is read at tmp == data_end, one byte beyond the region filled by skb_header_pointer(). irc_buffer is kmalloc'd as MAX_SEARCH_SIZE + 1 bytes and datalen is capped at MAX_SEARCH_SIZE, so the stray read does not fault. The byte is uninitialized or stale; if it contains an ASCII digit, simple_strtoul will consume it and produce a wrong DCC IP or port in the conntrack expectation. The extra allocation byte is also a fragile guard: if the cap or allocation size changes, this becomes a real out-of-bounds read. Change the loop and its post-loop check to use strict less-than, consistent with the caller's exclusive-end convention. Update the function comment accordingly.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/abb8c32b88ea3f46beb68c34fe9a3ac8ed664e7e
• https://git.kernel.org/stable/c/437e0a3854b3a44ec15afa9ab88ec215adf3a2fd
• https://git.kernel.org/stable/c/910c33e4a8c046c3cc1fa5a465a4d41a1bb398f1
• https://git.kernel.org/stable/c/2b70f61f569bb29acb380e6f616a1bbdee15668f
• https://git.kernel.org/stable/c/2393f0bd7a467ad475598f3a5b9de27ca36e3037
• https://git.kernel.org/stable/c/aff589556ed772cb1c0c2d7b4d91ec45c0c39416
• https://git.kernel.org/stable/c/eeef3b81f449560653662df2dde6f6fe247c5365
• https://git.kernel.org/stable/c/ef6400ca25a13fd6dedbe8ef4a1d0979bbbfe88a