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authorJeff Law <law@redhat.com>2012-02-29 11:51:27 -0500
committerCarlos O'Donell <carlos@codesourcery.com>2012-02-29 11:51:27 -0500
commit8fdceb2efda8cf724cfc4444af86b5f135ad3172 (patch)
tree82fca394d283dbc256d979675977ee3418ddbed3 /resolv
parent1f393a11f65dcaa1952bdcaf0317a65a5f8aff9d (diff)
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[network] Avoid out ouf bounds read in __libc_res_nquerydomain
2012-02-28  Jeff Law  <law@redhat.com>

	* resolv/res_query.c (__libc_res_nquerydomain): Avoid
	out of bounds read.
Diffstat (limited to 'resolv')
-rw-r--r--resolv/res_query.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/resolv/res_query.c b/resolv/res_query.c
index 947c6513a2..abccd4a921 100644
--- a/resolv/res_query.c
+++ b/resolv/res_query.c
@@ -556,12 +556,16 @@ __libc_res_nquerydomain(res_state statp,
 		 * copy without '.' if present.
 		 */
 		n = strlen(name);
-		if (n >= MAXDNAME) {
+
+		/* Decrement N prior to checking it against MAXDNAME
+		   so that we detect a wrap to SIZE_MAX and return
+		   a reasonable error.  */
+		n--;
+		if (n >= MAXDNAME - 1) {
 			RES_SET_H_ERRNO(statp, NO_RECOVERY);
 			return (-1);
 		}
-		n--;
-		if (n >= 0 && name[n] == '.') {
+		if (name[n] == '.') {
 			strncpy(nbuf, name, n);
 			nbuf[n] = '\0';
 		} else