[alsa-devel] [PATCH 2/2] alsaucm: Don't double-free empty lists

[Stephen Warren]

When snd_use_case_get_list (and hence also snd_use_case_card_list) returns
an empty list, alsaucm still attempts to free it. This ends up double-
freeing the returned list, or worse, freeing an invalid pointer, depending
on how snd_use_case_get_list gets implemented. Fix alsaucm to return early
on empty lists to avoid this.

Signed-off-by: Stephen Warren <swarren at nvidia.com>
---
 alsaucm/usecase.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/alsaucm/usecase.c b/alsaucm/usecase.c
index f24e63e..1c94680 100644
--- a/alsaucm/usecase.c
+++ b/alsaucm/usecase.c
@@ -226,8 +226,10 @@ static int do_one(struct context *context, struct cmd *cmd, char **argv)
 				snd_strerror(err));
 			return err;
 		}
-		if (err == 0)
+		if (err == 0) {
 			printf("  list is empty\n");
+			return 0;
+		}
 		for (i = 0; i < err / 2; i++) {
 			printf("  %i: %s\n", i, list[i*2]);
 			if (list[i*2+1])
@@ -256,8 +258,10 @@ static int do_one(struct context *context, struct cmd *cmd, char **argv)
 				snd_strerror(err));
 			return err;
 		}
-		if (err == 0)
+		if (err == 0) {
 			printf("  list is empty\n");
+			return 0;
+		}
 		for (i = 0; i < err / entries; i++) {
 			printf("  %i: %s\n", i, list[i*entries]);
 			for (j = 0; j < entries - 1; j++)
-- 
1.7.0.4