context: Don't create channels mask when IIO device has 0 channels

When a IIO device has 0 channels, there's no point in creating a channels mask. This fixes an undefined behaviour, as the call to iio_create_channels_mask() could result in calling malloc(0). To prevent this from happening again, iio_create_channels_mask() will now check the validity of its parameter. Signed-off-by: Paul Cercueil <[email protected]>
analogdevicesinc · Aug 23, 2022 · 9958d44 · 9958d44
1 parent 3e7d3b4
commit 9958d44
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Showing 2 changed files with 8 additions and 3 deletions.
diff --git a/context.c b/context.c
@@ -365,9 +365,11 @@ int iio_context_init(struct iio_context *ctx)
 	int ret;
 
 	for (i = 0; i < ctx->nb_devices; i++) {
-		ret = iio_device_alloc_mask(ctx->devices[i]);
-		if (ret)
-			return ret;
+		if (ctx->devices[i]->nb_channels) {
+			ret = iio_device_alloc_mask(ctx->devices[i]);
+			if (ret)
+				return ret;
+		}
 	}
 
 	for (i = 0; i < ctx->nb_devices; i++)

diff --git a/mask.c b/mask.c
@@ -16,6 +16,9 @@ struct iio_channels_mask * iio_create_channels_mask(unsigned int nb_channels)
 	struct iio_channels_mask *mask;
 	size_t nb_words = (nb_channels + 31) / 32;
 
+	if (!nb_words)
+		return NULL;
+
 	mask = zalloc(sizeof(*mask) + nb_words * sizeof(uint32_t));
 	if (mask)
 		mask->words = nb_words;