[Linux-kernel-mentees] [PATCH] net: team: fix memory leak in __team_options_register

Anant Thazhemadam anant.thazhemadam at gmail.com
Sun Oct 4 20:55:36 UTC 2020

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 at syzkaller.appspotmail.com
Tested-by: syzbot+69b804437cfec30deac3 at syzkaller.appspotmail.com
Signed-off-by: Anant Thazhemadam <anant.thazhemadam at gmail.com>
 drivers/net/team/team.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index 8c1e02752ff6..8986f3ffffe4 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -287,7 +287,7 @@ static int __team_options_register(struct team *team,
 	for (i--; i >= 0; i--)
 		__team_option_inst_del_option(team, dst_opts[i]);
-	i = option_count - 1;
+	i = option_count;
 	for (i--; i >= 0; i--)

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