commit e37ca0090343e0dae97e967d467bab56d502c37a
author Nikias Bassen <nikias@gmx.li> Sat Feb 18 18:09:34 2017 +0100
committer Nikias Bassen <nikias@gmx.li> Sat Feb 18 18:09:34 2017 +0100
tree 583595b3cbfa4f915924c7fdf4b7e8bbc36c70ae
parent 8ad21e6b59e5e5a3104660f17ad2b0e9122edecf

base64: Prevent undefined shift when parsing invalid base64 encoded data

Credit to OSS-Fuzz

src/base64.c

diff --git a/src/base64.c b/src/base64.c
index ba8acca..ee02356 100644
--- a/src/base64.c
+++ b/src/base64.c
@@ -101,13 +101,13 @@
 			w3 = tmpval[2];
 			w4 = tmpval[3];
 
-			if (w2 >= 0) {
+			if (w1 >= 0 && w2 >= 0) {
 				outbuf[p++] = (unsigned char)(((w1 << 2) + (w2 >> 4)) & 0xFF);
 			}
-			if (w3 >= 0) {
+			if (w2 >= 0 && w3 >= 0) {
 				outbuf[p++] = (unsigned char)(((w2 << 4) + (w3 >> 2)) & 0xFF);
 			}
-			if (w4 >= 0) {
+			if (w3 >= 0 && w4 >= 0) {
 				outbuf[p++] = (unsigned char)(((w3 << 6) + w4) & 0xFF);
 			}
 		}