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From:   Hangyu Hua <hbh25y@gmail.com>
To:     ericvh@kernel.org, lucho@ionkov.net, asmadeus@codewreck.org,
        linux_oss@crudebyte.com, davem@davemloft.net, edumazet@google.com,
        kuba@kernel.org, pabeni@redhat.com, jvrao@linux.vnet.ibm.com
Cc:     v9fs@lists.linux.dev, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Hangyu Hua <hbh25y@gmail.com>
Subject: [PATCH] net: 9p: fix possible memory leak in p9_check_errors()
Date:   Thu, 26 Oct 2023 17:23:51 +0800
Message-Id: <20231026092351.30572-1-hbh25y@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

When p9pdu_readf is called with "s?d" attribute, it allocates a pointer
that will store a string. But when p9pdu_readf() fails while handling "d"
then this pointer will not be freed in p9_check_errors.

Fixes: ca41bb3e21d7 ("[net/9p] Handle Zero Copy TREAD/RERROR case in !dotl case.")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
---
 net/9p/client.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/9p/client.c b/net/9p/client.c
index 86bbc7147fc1..6c7cd765b714 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -540,12 +540,15 @@ static int p9_check_errors(struct p9_client *c, struct p9_req_t *req)
 		return 0;
 
 	if (!p9_is_proto_dotl(c)) {
-		char *ename;
+		char *ename = NULL;
 
 		err = p9pdu_readf(&req->rc, c->proto_version, "s?d",
 				  &ename, &ecode);
-		if (err)
+		if (err) {
+			if (ename != NULL)
+				kfree(ename);
 			goto out_err;
+		}
 
 		if (p9_is_proto_dotu(c) && ecode < 512)
 			err = -ecode;
-- 
2.34.1