ALSA: Don't assume i2c device probing always succeeds

The client->driver pointer can be NULL when i2c-device probing fails
in i2c_new_device().  This patch adds the NULL checks for client->driver
and return the error instead of blind assumption of driver availability.

Reported-by: Tim Shepard <shep@alum.mit.edu>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 12 insertions, 0 deletions

diff --git a/sound/ppc/keywest.c b/sound/ppc/keywest.c
index 835fa19ed461..bb6819aab133 100644
--- a/sound/ppc/keywest.c
+++ b/sound/ppc/keywest.c
@@ -59,6 +59,18 @@ static int keywest_attach_adapter(struct i2c_adapter *adapter)
         strlcpy(info.type, "keywest", I2C_NAME_SIZE);
         info.addr = keywest_ctx->addr;
         keywest_ctx->client = i2c_new_device(adapter, &info);
+        if (!keywest_ctx->client)
+                return -ENODEV;
+        /*
+         * We know the driver is already loaded, so the device should be
+         * already bound. If not it means binding failed, and then there
+         * is no point in keeping the device instantiated.
+         */
+        if (!keywest_ctx->client->driver) {
+                i2c_unregister_device(keywest_ctx->client);
+                keywest_ctx->client = NULL;
+                return -ENODEV;
+        }
         
         /*
          * Let i2c-core delete that device on driver removal.