svn commit: r269873 - head/lib/libc/nameser
Hajimu UMEMOTO
ume at FreeBSD.org
Tue Aug 12 13:09:33 UTC 2014
Author: ume
Date: Tue Aug 12 13:09:32 2014
New Revision: 269873
URL: http://svnweb.freebsd.org/changeset/base/269873
Log:
Fix broken pointer overflow check ns_name_unpack()
Many compilers may optimize away the overflow check `msg + l < msg',
where `msg' is a pointer and `l' is an integer, because pointer
overflow is undefined behavior in C.
Use a safe precondition test `l >= eom - msg' instead.
Reference:
https://android-review.googlesource.com/#/c/50570/
Requested by: pfg
Obtained from: NetBSD (CVS rev. 1.10)
Modified:
head/lib/libc/nameser/ns_name.c
Directory Properties:
head/lib/libc/ (props changed)
Modified: head/lib/libc/nameser/ns_name.c
==============================================================================
--- head/lib/libc/nameser/ns_name.c Tue Aug 12 12:45:30 2014 (r269872)
+++ head/lib/libc/nameser/ns_name.c Tue Aug 12 13:09:32 2014 (r269873)
@@ -463,11 +463,12 @@ ns_name_unpack2(const u_char *msg, const
}
if (len < 0)
len = srcp - src + 1;
- srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
- if (srcp < msg || srcp >= eom) { /*%< Out of range. */
+ l = ((n & 0x3f) << 8) | (*srcp & 0xff);
+ if (l >= eom - msg) { /*%< Out of range. */
errno = EMSGSIZE;
return (-1);
}
+ srcp = msg + l;
checked += 2;
/*
* Check for loops in the compressed name;
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