Subject: [PATCH AUTOSEL 4.4 7/9] slcan: Fix memory leak in error path

From: Sasha Levin <[email-masked]>
Date: Fri, 22 Nov 2019 14:50:12 -0500

From: Jouni Hogander <[email-masked]>

[ Upstream commit ed50e1600b4483c049ce76e6bd3b665a6a9300ed ]

This patch is fixing memory leak reported by Syzkaller:

BUG: memory leak unreferenced object 0xffff888067f65500 (size 4096):
  comm "syz-executor043", pid 454, jiffies 4294759719 (age 11.930s)
  hex dump (first 32 bytes):
    73 6c 63 61 6e 30 00 00 00 00 00 00 00 00 00 00 slcan0..........
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
  backtrace:
    [<00000000a06eec0d>] __kmalloc+0x18b/0x2c0
    [<0000000083306e66>] kvmalloc_node+0x3a/0xc0
    [<000000006ac27f87>] alloc_netdev_mqs+0x17a/0x1080
    [<0000000061a996c9>] slcan_open+0x3ae/0x9a0
    [<000000001226f0f9>] tty_ldisc_open.isra.1+0x76/0xc0
    [<0000000019289631>] tty_set_ldisc+0x28c/0x5f0
    [<000000004de5a617>] tty_ioctl+0x48d/0x1590
    [<00000000daef496f>] do_vfs_ioctl+0x1c7/0x1510
    [<0000000059068dbc>] ksys_ioctl+0x99/0xb0
    [<000000009a6eb334>] __x64_sys_ioctl+0x78/0xb0
    [<0000000053d0332e>] do_syscall_64+0x16f/0x580
    [<0000000021b83b99>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
    [<000000008ea75434>] 0xffffffffffffffff

Cc: Wolfgang Grandegger <[email-masked]>
Cc: Marc Kleine-Budde <[email-masked]>
Cc: Lukas Bulwahn <[email-masked]>
Signed-off-by: Jouni Hogander <[email-masked]>
Signed-off-by: Marc Kleine-Budde <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 drivers/net/can/slcan.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
index 9a3f15cb7ef48..9b9dfa167ffbd 100644
--- a/drivers/net/can/slcan.c
+++ b/drivers/net/can/slcan.c
@@ -613,6 +613,7 @@ static int slcan_open(struct tty_struct *tty)
 	sl->tty = NULL;
 	tty->disc_data = NULL;
 	clear_bit(SLF_INUSE, &sl->flags);
+	free_netdev(sl->dev);
 
 err_exit:
 	rtnl_unlock();
-- 
2.20.1