libalpm/signing.c: Fix calculation of packet size in parse_subpacket

Given RFC 4880 provides the code to do this calculation, I am not sure
how I managed to stuff that up!  This bug was only exposed when a
signature made with "include-key-block" was added to the Arch repos,
which provided a subpacket with the required size to hit this issue.

Signed-off-by: Allan McRae <allan@archlinux.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/libalpm/signing.c b/lib/libalpm/signing.c
index c8eaaca2..2cbbd103 100644
--- a/lib/libalpm/signing.c
+++ b/lib/libalpm/signing.c
@@ -1058,7 +1058,7 @@ static int parse_subpacket(alpm_handle_t *handle, const char *identifier,
 				if(length_check(len, spos, 2, handle, identifier) != 0){
 					return -1;
 				}
-				slen = (sig[spos] << 8) | sig[spos + 1];
+				slen = ((sig[spos] - 192) << 8) + sig[spos + 1] + 192;
 				spos = spos + 2;
 			} else {
 				if(length_check(len, spos, 5, handle, identifier) != 0) {