[PATCH v2] mctp i3c: Fix locking in an error path

[Bart Van Assche]

If netdev_alloc_skb() fails, mctp_i3c_read() jumps to a label that
unlocks mi->lock although that mutex has not been locked yet. Fix this
by returning -ENOMEM directly. This bug has been detected by the Clang
thread-safety analyzer.

Cc: Leo Yang <Leo-Yang@xxxxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: Jeremy Kerr <jk@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Johnston <matt@xxxxxxxxxxxxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Fixes: 2d2d4f60ed26 ("mctp i3c: fix MCTP I3C driver multi-thread issue")
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
v1 -> v2:
- Return -ENOMEM directly upon allocation failure instead of adding a
  free_skb label.

 drivers/net/mctp/mctp-i3c.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/mctp/mctp-i3c.c b/drivers/net/mctp/mctp-i3c.c
index 4e857dd5df64..5f225999d715 100644
--- a/drivers/net/mctp/mctp-i3c.c
+++ b/drivers/net/mctp/mctp-i3c.c
@@ -111,8 +111,7 @@ static int mctp_i3c_read(struct mctp_i3c_device *mi)
 			       mi->mrl + sizeof(struct mctp_i3c_internal_hdr));
 	if (!skb) {
 		stats->rx_dropped++;
-		rc = -ENOMEM;
-		goto err;
+		return -ENOMEM;
 	}
 
 	skb->protocol = htons(ETH_P_MCTP);