[050/105] ROSE: prevent heap corruption with bad facilities

Greg KH
2011-04-12T14:38:21Z

From: Dan Rosenberg <drosenberg@vsecurity.com>

commit be20250c13f88375345ad99950190685eda51eb8 upstream.

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
net/rose/rose_subr.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)

--- a/net/rose/rose_subr.c
+++ b/net/rose/rose_subr.c
@@ -290,10 +290,15 @@ static int rose_parse_national(unsigned
facilities->source_ndigis = 0;
facilities->dest_ndigis = 0;
for (pt = p + 2, lg = 0 ; lg < l ; pt += AX25_ADDR_LEN, lg += AX25_ADDR_LEN) {
- if (pt[6] & AX25_HBIT)
+ if (pt[6] & AX25_HBIT) {
+ if (facilities->dest_ndigis >= ROSE_MAX_DIGIS)
+ return -1;
memcpy(&facilities->dest_digis[facilities->dest_ndigis++], pt, AX25_ADDR_LEN);
- else
+ } else {
+ if (facilities->source_ndigis >= ROSE_MAX_DIGIS)
+ return -1;
memcpy(&facilities->source_digis[facilities->source_ndigis++], pt, AX25_ADDR_LEN);
+ }
}
}
p += l + 2;
@@ -333,6 +338,11 @@ static int rose_parse_ccitt(unsigned cha

case 0xC0:
l = p[1];
+
+ /* Prevent overflows*/
+ if (l < 10 || l > 20)
+ return -1;
+
if (*p == FAC_CCITT_DEST_NSAP) {
memcpy(&facilities->source_addr, p + 7, ROSE_ADDR_LEN);
memcpy(callsign, p + 12, l - 10);
@@ -373,12 +383,16 @@ int rose_parse_facilities(unsigned char
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;