Code: int rose_parse_facilities(unsigned char *p,
	struct rose_facilities_struct *facilities)
{
	int facilities_len, len;

	facilities_len = *p++;

	if (facilities_len == 0)
		return 0;

	while (facilities_len > 0) {
		if (*p == 0x00) {
			facilities_len--;
			p++;

 			switch (*p) {
 			case FAC_NATIONAL:		/* National */
 				len = rose_parse_national(p + 1, facilities, facilities_len - 1);
 				facilities_len -= len + 1;
 				p += len + 1;
 				break;
 
 			case FAC_CCITT:		/* CCITT */
 				len = rose_parse_ccitt(p + 1, facilities, facilities_len - 1);
 				facilities_len -= len + 1;
 				p += len + 1;
 				break;

			default:
				printk(KERN_DEBUG "ROSE: rose_parse_facilities - unknown facilities family %02X\n", *p);
				facilities_len--;
				p++;
				break;
			}
		} else
			break;	/* Error in facilities format */
	}

	return 1;
}

Commit Message: ROSE: prevent heap corruption with bad facilities

When parsing the FAC_NATIONAL_DIGIS facilities field, it's possible for
a remote host to provide more digipeaters than expected, resulting in
heap corruption.  Check against ROSE_MAX_DIGIS to prevent overflows, and
abort facilities parsing on failure.

Additionally, when parsing the FAC_CCITT_DEST_NSAP and
FAC_CCITT_SRC_NSAP facilities fields, a remote host can provide a length
of less than 10, resulting in an underflow in a memcpy size, causing a
kernel panic due to massive heap corruption.  A length of greater than
20 results in a stack overflow of the callsign array.  Abort facilities
parsing on these invalid length values.

Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: stable@kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
CWE ID: CWE-20
int rose_parse_facilities(unsigned char *p,
	struct rose_facilities_struct *facilities)
{
	int facilities_len, len;

	facilities_len = *p++;

	if (facilities_len == 0)
		return 0;

	while (facilities_len > 0) {
		if (*p == 0x00) {
			facilities_len--;
			p++;

 			switch (*p) {
 			case FAC_NATIONAL:		/* National */
 				len = rose_parse_national(p + 1, facilities, facilities_len - 1);
				if (len < 0)
					return 0;
 				facilities_len -= len + 1;
 				p += len + 1;
 				break;
 
 			case FAC_CCITT:		/* CCITT */
 				len = rose_parse_ccitt(p + 1, facilities, facilities_len - 1);
				if (len < 0)
					return 0;
 				facilities_len -= len + 1;
 				p += len + 1;
 				break;

			default:
				printk(KERN_DEBUG "ROSE: rose_parse_facilities - unknown facilities family %02X\n", *p);
				facilities_len--;
				p++;
				break;
			}
		} else
			break;	/* Error in facilities format */
	}

	return 1;
}
