linux-kernel - [PATCH v2] misc: fastrpc: fix potential fastrpc_invoke

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Date:   Tue, 12 May 2020 12:09:30 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        arnd@...db.de,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH v2] misc: fastrpc: fix potential fastrpc_invoke_ctx leak

fastrpc_invoke_ctx can have refcount of 2 in error path where
rpmsg_send() fails to send invoke message. decrement the refcount
properly in the error path to fix this leak.

This also fixes below static checker warning:

drivers/misc/fastrpc.c:990 fastrpc_internal_invoke()
warn: 'ctx->refcount.refcount.ref.counter' not decremented on lines: 990.

Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context")
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
Changes since v1:
	moved fastrpc_context_put to fastrpc_invoke_send()

 drivers/misc/fastrpc.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 9065d3e71ff7..7939c55daceb 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -904,6 +904,7 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
 	struct fastrpc_channel_ctx *cctx;
 	struct fastrpc_user *fl = ctx->fl;
 	struct fastrpc_msg *msg = &ctx->msg;
+	int ret;
 
 	cctx = fl->cctx;
 	msg->pid = fl->tgid;
@@ -919,7 +920,13 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
 	msg->size = roundup(ctx->msg_sz, PAGE_SIZE);
 	fastrpc_context_get(ctx);
 
-	return rpmsg_send(cctx->rpdev->ept, (void *)msg, sizeof(*msg));
+	ret = rpmsg_send(cctx->rpdev->ept, (void *)msg, sizeof(*msg));
+
+	if (ret)
+		fastrpc_context_put(ctx);
+
+	return ret;
+
 }
 
 static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
-- 
2.21.0