Author: emaste Date: Tue Nov 25 18:39:37 2014 New Revision: 275060 URL: https://svnweb.freebsd.org/changeset/base/275060
Log: Fix b64_pton output buffer overrun test for exact-sized buffer b64_pton would sometimes erroneously fail to decode a base64 string into a precisely sized buffer. The overflow check was a little too greedy. Reported by: Ted Unangst on freebsd-hackers@ Reviewed by: loos, trasz Obtained from: OpenBSD MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D1218 Modified: head/lib/libc/net/base64.c Modified: head/lib/libc/net/base64.c ============================================================================== --- head/lib/libc/net/base64.c Tue Nov 25 18:35:47 2014 (r275059) +++ head/lib/libc/net/base64.c Tue Nov 25 18:39:37 2014 (r275060) @@ -199,6 +199,7 @@ b64_pton(src, target, targsize) size_t targsize; { int tarindex, state, ch; + u_char nextbyte; char *pos; state = 0; @@ -226,22 +227,28 @@ b64_pton(src, target, targsize) break; case 1: if (target) { - if ((size_t)tarindex + 1 >= targsize) + if ((size_t)tarindex >= targsize) return (-1); target[tarindex] |= (pos - Base64) >> 4; - target[tarindex+1] = ((pos - Base64) & 0x0f) - << 4 ; + nextbyte = ((pos - Base64) & 0x0f) << 4; + if ((size_t)tarindex + 1 < targsize) + target[tarindex + 1] = nextbyte; + else if (nextbyte) + return (-1); } tarindex++; state = 2; break; case 2: if (target) { - if ((size_t)tarindex + 1 >= targsize) + if ((size_t)tarindex >= targsize) return (-1); target[tarindex] |= (pos - Base64) >> 2; - target[tarindex+1] = ((pos - Base64) & 0x03) - << 6; + nextbyte = ((pos - Base64) & 0x03) << 6; + if ((size_t)tarindex + 1 < targsize) + target[tarindex + 1] = nextbyte; + else if (nextbyte) + return (-1); } tarindex++; state = 3; @@ -299,7 +306,8 @@ b64_pton(src, target, targsize) * zeros. If we don't check them, they become a * subliminal channel. */ - if (target && target[tarindex] != 0) + if (target && (size_t)tarindex < targsize && + target[tarindex] != 0) return (-1); } } else { _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
