On 04/11/16 at 10:51am, Will Miles wrote:
> This patch fixes several places where an unavailable (NULL) backup hash may be
> passed to a printf() call, which segfaults on some libcs. This includes
> local database writes where unavailable hashes are represented by the file
> name only. This condition may occur when an updated package changes the
> contents of its backup=() list.
>
> Signed-off-by: Will Miles
> ---
> lib/libalpm/add.c | 6 +++---
> lib/libalpm/be_local.c | 6 +-
> 2 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/lib/libalpm/add.c b/lib/libalpm/add.c
> index f5c9a95..629e2a5 100644
> --- a/lib/libalpm/add.c
> +++ b/lib/libalpm/add.c
> @@ -339,9 +339,9 @@ static int extract_single_file(alpm_handle_t *handle,
> struct archive *archive,
> hash_pkg = backup ? backup->hash :
> alpm_compute_md5sum(filename);
>
> _alpm_log(handle, ALPM_LOG_DEBUG, "checking hashes for %s\n",
> origfile);
> - _alpm_log(handle, ALPM_LOG_DEBUG, "current: %s\n", hash_local);
> - _alpm_log(handle, ALPM_LOG_DEBUG, "new: %s\n", hash_pkg);
> - _alpm_log(handle, ALPM_LOG_DEBUG, "original: %s\n", hash_orig);
> + _alpm_log(handle, ALPM_LOG_DEBUG, "current: %s\n", (hash_local
> ? hash_local : "NULL") );
> + _alpm_log(handle, ALPM_LOG_DEBUG, "new: %s\n", (hash_pkg ?
> hash_pkg : "NULL") );
> + _alpm_log(handle, ALPM_LOG_DEBUG, "original: %s\n", (hash_orig
> ? hash_orig : "NULL") );
>
> if(hash_local && hash_pkg && strcmp(hash_local, hash_pkg) == 0)
> {
> /* local and new files are the same, updating anyway to
> get
> diff --git a/lib/libalpm/be_local.c b/lib/libalpm/be_local.c
> index f817822..21166cb 100644
> --- a/lib/libalpm/be_local.c
> +++ b/lib/libalpm/be_local.c
> @@ -1037,7 +1037,11 @@ int _alpm_local_db_write(alpm_db_t *db, alpm_pkg_t
> *info, alpm_dbinfrq_t inforeq
> fputs("%BACKUP%\n", fp);
> for(lp = info->backup; lp; lp = lp->next) {
> const alpm_backup_t *backup = lp->data;
> - fprintf(fp, "%s\t%s\n", backup->name,
> backup->hash);
> + if (backup->hash) {
> + fprintf(fp, "%s\t%s\n", backup->name,
> backup->hash);
> + } else {
> + fprintf(fp, "%s\n", backup->name);
This will break the parser if the file name contains a tab. Just do
something similar to what you did above:
fprintf(fp, "%s\t%s\n", backup->name, backup->hash ? backup->hash : "");
The parser also needs to be updated to use strrchr instead of strchr
for the same reason, but that's another patch.
> + }
> }
> fputc('\n', fp);
> }
> --
> 2.6.3
