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gpg: Fix out-of-bound read in subpacket enumeration

Browse Source 
* g10/parse-packet.c (enum_sig_subpkt): Check buflen before reading
the type octet.  Print diagnostic.
--

If the final subpacket has only a length header evaluating to zero and
missing the type octet, a read could happen right behind the buffer.
Valgrind detected this.  Fix is obvious.  Note that the further
parsing of the subpacket is still okay because it always checks the
length.  Note further that --list-packets uses a different code path
and already reported an error.

Reported-by: Philippe Antoine

He provided a test file copied below.  Running "gpg -v --verify" on it
triggered the bug.

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Comment: Use "gpg --dearmor" for unpacking

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Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch 2018-03-15 08:44:52 +01:00
parent 11bbd99477
commit 983f7b2acb
No known key found for this signature in database
GPG Key ID: E3FDFF218E45B72B
1 changed files with 9 additions and 0 deletions
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9
g10/parse-packet.c
View File

@ -1702,6 +1702,8 @@ enum_sig_subpkt (const subpktarea_t * pktbuf, sigsubpkttype_t reqtype,
}
if (buflen < n)
goto too_short;
if (!buflen)
goto no_type_byte;
type = *buffer;
if (type & 0x80)
{
@ -1776,6 +1778,13 @@ enum_sig_subpkt (const subpktarea_t * pktbuf, sigsubpkttype_t reqtype,
if (start)
*start = -1;
return NULL;
no_type_byte:
if (opt.verbose)
log_info ("type octet missing in subpacket\n");
if (start)
*start = -1;
return NULL;
}