On (09/08/15 10:39), Luis Henriques wrote:
> zcomp_create() verifies the success of zcomp_strm_{multi,siggle}_create()
> through comp->stream, which can potentially be pointing to memory that was
> freed if these functions returned an error.
>
> While at it, replace a 'ERR_PTR(-ENOMEM)' by a more generic
> 'ERR_PTR(error)' as in the future zcomp_strm_{multi,siggle}_create() could
> return other error codes. Function documentation updated accordingly.
>
> Fixes: beca3ec71fe5 ("zram: add multi stream functionality")
> Cc: sta...@vger.kernel.org
> Cc: Sergey Senozhatsky <sergey.senozhatsky.w...@gmail.com>
> Cc: Minchan Kim <minc...@kernel.org>
> Signed-off-by: Luis Henriques <luis.henriq...@canonical.com>
Acked-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com>
-ss
> ---
>
> Changes since v2:
> * Renamed local variable 'ret' to 'error'
> * Usage of 'ERR_PTR(error)' to accommodate future error codes returned by
> zcomp_strm_{multi,siggle}_create
> (all suggested by Minchan)
>
> Changes since v1:
> * Check zcomp_strm_{multi,siggle}_create() return code instead
> comp->stream (suggested by Sergey)
>
> drivers/block/zram/zcomp.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
> index 965d1afb0eaa..5cb13ca3a3ac 100644
> --- a/drivers/block/zram/zcomp.c
> +++ b/drivers/block/zram/zcomp.c
> @@ -330,12 +330,14 @@ void zcomp_destroy(struct zcomp *comp)
> * allocate new zcomp and initialize it. return compressing
> * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
> * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
> - * case of allocation error.
> + * case of allocation error, or any other error potentially
> + * returned by functions zcomp_strm_{multi,single}_create.
> */
> struct zcomp *zcomp_create(const char *compress, int max_strm)
> {
> struct zcomp *comp;
> struct zcomp_backend *backend;
> + int error;
>
> backend = find_backend(compress);
> if (!backend)
> @@ -347,12 +349,12 @@ struct zcomp *zcomp_create(const char *compress, int
> max_strm)
>
> comp->backend = backend;
> if (max_strm > 1)
> - zcomp_strm_multi_create(comp, max_strm);
> + error = zcomp_strm_multi_create(comp, max_strm);
> else
> - zcomp_strm_single_create(comp);
> - if (!comp->stream) {
> + error = zcomp_strm_single_create(comp);
> + if (error) {
> kfree(comp);
> - return ERR_PTR(-ENOMEM);
> + return ERR_PTR(error);
> }
> return comp;
> }
>
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