Affected: Linux

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.