Re: [PATCH v2] dm-pcache: reject option groups without values

On Mon, Jun 29, 2026 at 11:48 PM Samuel Moelius
<[email protected]> wrote:
>
> The pcache target parses optional arguments as name/value pairs.  A
> table that advertises one optional argument and supplies only a
> recognized option name, for example "cache_mode", reaches
> parse_cache_opts() with argc == 1.  The parser consumes the name,
> decrements argc to zero, then calls dm_shift_arg() again for the value.
> dm_shift_arg() returns NULL when no arguments remain, and the following
> strcmp() dereferences that NULL pointer.
>
> Check that each recognized option has a value before consuming it.  This
> keeps valid "cache_mode writeback" and "data_crc true/false" tables
> unchanged while making malformed tables fail during target construction
> with a precise missing-value error.
>
> Assisted-by: Codex:gpt-5.5-cyber-preview
> Signed-off-by: Samuel Moelius <[email protected]>
> ---
> Changes in v2:
>   - Verify required arguments in a more flexible way
>
>  drivers/md/dm-pcache/dm_pcache.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/md/dm-pcache/dm_pcache.c b/drivers/md/dm-pcache/dm_pcache.c
> index 81c795c0400e..d5cfd162c063 100644
> --- a/drivers/md/dm-pcache/dm_pcache.c
> +++ b/drivers/md/dm-pcache/dm_pcache.c
> @@ -168,6 +168,10 @@ static int parse_cache_opts(struct dm_pcache *pcache, struct dm_arg_set *as,
>                 argc--;
>
>                 if (!strcmp(arg, "cache_mode")) {
> +                       if (!argc) {
> +                               *error = "Missing value for cache_mode";
> +                               return -EINVAL;
> +                       }
>                         arg = dm_shift_arg(as);
>                         if (!strcmp(arg, "writeback")) {
>                                 opts->cache_mode = PCACHE_CACHE_MODE_WRITEBACK;
> @@ -177,6 +181,10 @@ static int parse_cache_opts(struct dm_pcache *pcache, struct dm_arg_set *as,
>                         }
>                         argc--;
>                 } else if (!strcmp(arg, "data_crc")) {
> +                       if (!argc) {
> +                               *error = "Missing value for data_crc";
> +                               return -EINVAL;
> +                       }
>                         arg = dm_shift_arg(as);
>                         if (!strcmp(arg, "true")) {
>                                 opts->data_crc = true;
> --
> 2.43.0
>

Reviewed-by:  Zheng Gu <[email protected]>