A memory leak and out-of-bounds write was found in fpm_log.c.

At line 237 (php 5.6.14):
len2 = snprintf(b, FPM_LOG_BUFFER - len, "%s", env ? env : "-");

The functions snprintf() and vsnprintf() do not write more than size bytes (including the terminating null byte ('\0')). If the output was truncated due to this limit then the return value is the number of characters (excluding the terminating null byte) which would have been written to the final string if enough space had been available.


The full length (len) is increased by len2 (line 449):
len += len2;

After exiting the loop, a \n byte is written outside of the compiled buffer and the log line along with some memory area lying after it is flushed into the access log:

	if (!test && strlen(buffer) > 0) {
 		buffer[len] = '\n';
		write(fpm_log_fd, buffer, len + 1);
	}

This results in one byte written out-of-bounds and several bytes read out-of-bounds.

Upstream patch:

https://git.php.net/?p=php-src.git;a=commitdiff;h=2721a0148649e07ed74468f097a28899741eb58f

Upstream bug (contains reproducer):

https://bugs.php.net/bug.php?id=70755