[pacman-dev] [PATCH] Check for all return values of _alpm_key_in_keychain

[Andrew Gregory]

On 04/21/17 at 04:07pm, David Phillips wrote:
> This fixes a bug I encountered with a GPG keyring where the
> key id used to locate a key in the keyring was ambiguous within
> my keychain.
> 
> This commit ensures that all valid return values are checked to
> catch this and related error cases rather than incorrectly taking
> an error case to mean the key was found, since this is rarely going
> to be the case.
> ---
>  lib/libalpm/be_package.c | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/libalpm/be_package.c b/lib/libalpm/be_package.c
> index 7e8b7920..1891fa5a 100644
> --- a/lib/libalpm/be_package.c
> +++ b/lib/libalpm/be_package.c
> @@ -754,10 +754,21 @@ int SYMEXPORT alpm_pkg_load(alpm_handle_t *handle, const char *filename, int ful
>  				alpm_list_t *k;
>  				for(k = keys; k; k = k->next) {
>  					char *key = k->data;
> -					if(_alpm_key_in_keychain(handle, key) == 0) {
> -						if(_alpm_key_import(handle, key) == -1) {
> +					switch(_alpm_key_in_keychain(handle, key)) {
> +						case 1:
> +							/* key is known; proceed */
> +							break;
> +						case 0:
> +							/* key is unknown; attempt to import */
> +							if(_alpm_key_import(handle, key) == -1) {
> +								fail = 1;
> +							}
> +							break;
> +						case -1:
> +							/* error finding key in keychain */
> +						default:
>  							fail = 1;

Just below this, an error message is printed if fail is true, saying
that the key is missing.  If we got a generic code, that may not be
the case, and is the exact opposite of the problem that prompted
patch.

I'm wondering if this is necessary at all, though.  This bit of code
is specifically just for importing missing keys.  Any other
significant errors should be caught during the actual validation
attempt, where we already provide the actual gpg error message.  If
the gpgme segmentation fault is no longer an issue, do we gain
anything other than bailing out slightly sooner by adding the extra
check and complexity for printing an appropriate error message here?

> -						}
> +							break;
>  					}
>  				}
>  				FREELIST(keys);
> -- 
> 2.12.2