Fix out-of-bounds cursor increment in pop_token()

[94xhn]

While parsing tokens from the configuration file lines (and IPC parameters), \pop_token()\ traverses to the end of a token. When parsing the last token on a line, \end\ will point to the natural null terminator \0. Unconditionally incrementing the cursor *line = end + 1\ makes the next parsing loop reference memory past the buffer boundaries (an out-of-bounds read). If the adjacent memory is dirty (not null or whitespaces), \pop_token\ will process it as a token and write a null terminator *end = 0\ further out-of-bounds. This patch checks if *end == '\0'\ first. If it is, *line\ is safely set to \NULL\ to prevent subsequent parsing loops from running off the buffer. Otherwise, it proceeds with the usual null termination and cursor increment.

[troglobit]

Nice catch!