linux-kernel - [PATCH 4.9 39/54] net: team: fix memory leak in __team_options

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Message-Id: <20201012132631.387586022@linuxfoundation.org>
Date:   Mon, 12 Oct 2020 15:27:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+69b804437cfec30deac3@...kaller.appspotmail.com,
        Anant Thazhemadam <anant.thazhemadam@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 39/54] net: team: fix memory leak in __team_options_register

From: Anant Thazhemadam <anant.thazhemadam@...il.com>

commit 9a9e77495958c7382b2438bc19746dd3aaaabb8e upstream.

The variable "i" isn't initialized back correctly after the first loop
under the label inst_rollback gets executed.

The value of "i" is assigned to be option_count - 1, and the ensuing
loop (under alloc_rollback) begins by initializing i--.
Thus, the value of i when the loop begins execution will now become
i = option_count - 2.

Thus, when kfree(dst_opts[i]) is called in the second loop in this
order, (i.e., inst_rollback followed by alloc_rollback),
dst_optsp[option_count - 2] is the first element freed, and
dst_opts[option_count - 1] does not get freed, and thus, a memory
leak is caused.

This memory leak can be fixed, by assigning i = option_count (instead of
option_count - 1).

Fixes: 80f7c6683fe0 ("team: add support for per-port options")
Reported-by: syzbot+69b804437cfec30deac3@...kaller.appspotmail.com
Tested-by: syzbot+69b804437cfec30deac3@...kaller.appspotmail.com
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/team/team.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -299,7 +299,7 @@ inst_rollback:
 	for (i--; i >= 0; i--)
 		__team_option_inst_del_option(team, dst_opts[i]);

-	i = option_count - 1;
+	i = option_count;
 alloc_rollback:
 	for (i--; i >= 0; i--)
 		kfree(dst_opts[i]);