slip: Fix memory leak in slip_open error path

Driver/net/can/slcan.c is derived from slip.c. Memory leak was detected
by Syzkaller in slcan. Same issue exists in slip.c and this patch is
addressing the leak in slip.c.

Here is the slcan memory leak trace 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>] 0xfffffffffffffff

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Jouni Hogander <jouni.hogander@unikie.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/slip/slip.c b/drivers/net/slip/slip.c
index cac64b96d5451f2ee37e98baeb84ef538fd97562..4d479e3c817d8aa078eb347f6d61baa5c7b8a6c0 100644 (file)
--- a/drivers/net/slip/slip.c
+++ b/drivers/net/slip/slip.c
@@ -855,6 +855,7 @@ err_free_chan:
        sl->tty = NULL;
        tty->disc_data = NULL;
        clear_bit(SLF_INUSE, &sl->flags);
+       free_netdev(sl->dev);
 
 err_exit:
        rtnl_unlock();