[pacman-dev] [PATCH] libalpm: Do a sanity check before manipulating final DB URL

[Florian Pritz]

On 13.04.2015 21:33, David Macek wrote:
> diff --git a/lib/libalpm/be_sync.c b/lib/libalpm/be_sync.c
> index 20130dc..f30698e 100644
> --- a/lib/libalpm/be_sync.c
> +++ b/lib/libalpm/be_sync.c
> @@ -241,20 +241,27 @@ int SYMEXPORT alpm_db_update(int force, alpm_db_t *db)
>  			unlink(sigpath);
>  			free(sigpath);
>  
> -			/* if we downloaded a DB, we want the .sig from the same server -
> -			   this information is only available from the internal downloader */
> -			if(handle->fetchcb == NULL) {
> +
> +			/* check if the final URL from internal downloader looks reasonable */
> +			if(final_db_url != NULL) {
> +				if(strlen(final_db_url) < 3 || strcmp(final_db_url + strlen(final_db_url) - 3, ".db") != 0) {
> +					final_db_url = NULL;
> +				}
> +			}
> +
> +			/* if we downloaded a DB, we want the .sig from the same server */
> +			if(final_db_url != NULL) {
>  				/* print final_db_url into a buffer (leave space for .sig) */
>  				len = strlen(final_db_url) + 5;
>  			} else {
> -				/* print server + filename into a buffer (leave space for .sig) */
> +				/* print server + filename into a buffer (leave space for .db.sig) */
>  				len = strlen(server) + strlen(db->treename) + 9;

Comment changed, but not the code? If you know where that + 9 comes from
it might be a good idea to replace it with strlen("whatever") which the
compile should optimize out later, but writing it this way makes the
whole thing a lot clearer.

I'll let someone else comment on the rest of the patch.

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