From: Jonathan McDowell <noodles@earth.li>
Date: Mon, 22 Aug 2016 16:30:14 +0000 (+0100)
Subject: Prevent sign extension when parsing large packet sizes
X-Git-Tag: onak-0.5.0~6
X-Git-Url: https://the.earth.li/gitweb/?p=onak.git;a=commitdiff_plain;h=a75148cf51de7fe9112f5ba260e62828d5297979

Prevent sign extension when parsing large packet sizes

A 2GB+ packet is likely to be a mistake, but in the event it was
legitimate sign extension could result in a much larger amount of
memory being allocated (and probably failing). Fix this by trying
to ensure we're doing an unsigned left shift.
---

diff --git a/parsekey.c b/parsekey.c
index ed61e24..6255ab8 100644
--- a/parsekey.c
+++ b/parsekey.c
@@ -308,7 +308,7 @@ onak_status_t read_openpgp_stream(int (*getchar_func)(void *ctx, size_t count,
 						break;
 					}
 					curpacket->packet->length = 
-						(curchar << 24);
+						((unsigned) curchar << 24);
 					if (getchar_func(ctx, 1, &curchar)) {
 						rc = ONAK_E_INVALID_PKT;
 						break;