Re: [PATCH] dma-buf: fix uninitialized variable usage in selftests

[Nathan Chancellor <nathan@xxxxxxxxxx>]

Hi Christian,

On Mon, Oct 25, 2021 at 09:28:35AM +0200, Christian König wrote:
> "i" can be used uninitialized in one of the error branches. Fix this.
> 
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> ---
>  drivers/dma-buf/st-dma-resv.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dma-buf/st-dma-resv.c b/drivers/dma-buf/st-dma-resv.c
> index 6f3ba756da3e..bc2265807f6c 100644
> --- a/drivers/dma-buf/st-dma-resv.c
> +++ b/drivers/dma-buf/st-dma-resv.c
> @@ -295,7 +295,7 @@ static int test_get_fences(void *arg, bool shared)
>  		if (r) {
>  			pr_err("Resv shared slot allocation failed\n");
>  			dma_resv_unlock(&resv);
> -			goto err_free;
> +			goto err_fini;
>  		}
>  
>  		dma_resv_add_shared_fence(&resv, f);
> @@ -336,6 +336,7 @@ static int test_get_fences(void *arg, bool shared)
>  	while (i--)
>  		dma_fence_put(fences[i]);
>  	kfree(fences);
> +err_fini:
>  	dma_resv_fini(&resv);
>  	dma_fence_put(f);
>  	return r;
> -- 
> 2.25.1
> 
> 

Thanks for the patch! This is not enough to fix all the warnings in this
file:

drivers/dma-buf/st-dma-resv.c:288:6: error: variable 'i' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
        if (r) {
            ^
drivers/dma-buf/st-dma-resv.c:336:9: note: uninitialized use occurs here
        while (i--)
               ^
drivers/dma-buf/st-dma-resv.c:288:2: note: remove the 'if' if its condition is always false
        if (r) {
        ^~~~~~~~
drivers/dma-buf/st-dma-resv.c:280:10: note: initialize the variable 'i' to silence this warning
        int r, i;
                ^
                 = 0
1 error generated.

This hunk resolves it for me. With that:

Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx>

diff --git a/drivers/dma-buf/st-dma-resv.c b/drivers/dma-buf/st-dma-resv.c
index bc2265807f6c..e5d5c25eed53 100644
--- a/drivers/dma-buf/st-dma-resv.c
+++ b/drivers/dma-buf/st-dma-resv.c
@@ -287,7 +287,7 @@ static int test_get_fences(void *arg, bool shared)
 	r = dma_resv_lock(&resv, NULL);
 	if (r) {
 		pr_err("Resv locking failed\n");
-		goto err_free;
+		goto err_fini;
 	}
 
 	if (shared) {