Pi-Hole/dnsmasq
1
0
Fork 0
mirror of https://github.com/pi-hole/dnsmasq.git synced 2025-12-19 18:28:25 +00:00
Code Issues Packages Projects Releases Wiki Activity

Fix buffer overflow introduced in 2.73rc6.

Browse Source 
Fix off-by-one in code which checks for over-long domain names
in received DNS packets. This enables buffer overflow attacks
which can certainly crash dnsmasq and may allow for arbitrary
code execution. The problem was introduced in commit b8f16556d,
release 2.73rc6, so has not escaped into any stable release.
Note that the off-by-one was in the label length determination,
so the buffer can be overflowed by as many bytes as there are
labels in the name - ie, many.

Thanks to Ron Bowes, who used lcmatuf's afl-fuzz tool to find
the problem.
This commit is contained in:
Simon Kelley
2015-05-15 18:13:06 +01:00
parent 62018e1f72
commit 5d07d77e75
1 changed files with 4 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
src/rfc1035.c
View File

@@ -94,8 +94,8 @@ int extract_name(struct dns_header *header, size_t plen, unsigned char **pp,
count = 256;
digs = ((count-1)>>2)+1;
/* output is \[x<hex>/siz]. which is digs+6/7/8 chars */
namelen += digs+6;
/* output is \[x<hex>/siz]. which is digs+7/8/9 chars */
namelen += digs+7;
if (count > 9)
namelen++;
if (count > 99)
@@ -125,8 +125,8 @@ int extract_name(struct dns_header *header, size_t plen, unsigned char **pp,
}
else
{ /* label_type = 0 -> label. */
namelen += l;
if (namelen+1 >= MAXDNAME)
namelen += l + 1; /* include period */
if (namelen >= MAXDNAME)
return 0;
if (!CHECK_LEN(header, p, plen, l))
return 0;