Patchwork [v2] ROSE: prevent heap corruption with bad facilities

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Submitter Dan Rosenberg
Date March 20, 2011, 6:43 a.m.
Message ID <1300603423.1869.18.camel@dan>
Download mbox | patch
Permalink /patch/87649/
State Accepted
Delegated to: David Miller
Headers show

Comments

Dan Rosenberg - March 20, 2011, 6:43 a.m.
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
---
 net/rose/rose_subr.c |   18 ++++++++++++++++--
 1 files changed, 16 insertions(+), 2 deletions(-)



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David Miller - March 28, 2011, 12:59 a.m.
From: Dan Rosenberg <drosenberg@vsecurity.com>
Date: Sun, 20 Mar 2011 02:43:43 -0400

> 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

Applied.
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Patch

diff --git a/net/rose/rose_subr.c b/net/rose/rose_subr.c
index 1734abb..6f5f0b5 100644
--- a/net/rose/rose_subr.c
+++ b/net/rose/rose_subr.c
@@ -290,10 +290,15 @@  static int rose_parse_national(unsigned char *p, struct rose_facilities_struct *
 				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 char *p, struct rose_facilities_struct *fac
 
 		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 *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;