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1465. [bug] isc_base64_decodestring() and isc_base64_tobuffer()

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failed to check that trailing bits were zero allowing
                        some invalid base64 strings to be accepted.  [RT #5397]
This commit is contained in:
Mark Andrews
2003-04-17 06:04:13 +00:00
parent b0c2141b23
commit f5af519ab5
2 changed files with 16 additions and 1 deletions
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13
lib/isc/base64.c
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@@ -15,7 +15,7 @@
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/* $Id: base64.c,v 1.25 2001/11/27 01:55:53 gson Exp $ */
/* $Id: base64.c,v 1.26 2003/04/17 06:04:13 marka Exp $ */
#include <config.h>
@@ -126,6 +126,17 @@ base64_decode_char(base64_decode_ctx_t *ctx, int c) {
return (ISC_R_BADBASE64);
if (ctx->val[2] == 64 && ctx->val[3] != 64)
return (ISC_R_BADBASE64);
/*
* Check that bits that should be zero are.
*/
if (ctx->val[2] == 64 && (ctx->val[1] & 0xf) != 0)
return (ISC_R_BADBASE64);
/*
* We don't need to test for ctx->val[2] != 64 as
* the bottom two bits of 64 are zero.
*/
if (ctx->val[3] == 64 && (ctx->val[2] & 0x3) != 0)
return (ISC_R_BADBASE64);
n = (ctx->val[2] == 64) ? 1 :
(ctx->val[3] == 64) ? 2 : 3;
if (n != 3) {