From: Zheyu Ma zheyuma97@gmail.com
[ Upstream commit 689ca31c542687709ba21ec2195c1fbce34fd029 ]
When the driver fails at alloc_hdlcdev(), and then we remove the driver module, we will get the following splat:
[ 25.065966] general protection fault, probably for non-canonical address 0xdffffc0000000182: 0000 [#1] PREEMPT SMP KASAN PTI [ 25.066914] KASAN: null-ptr-deref in range [0x0000000000000c10-0x0000000000000c17] [ 25.069262] RIP: 0010:detach_hdlc_protocol+0x2a/0x3e0 [ 25.077709] Call Trace: [ 25.077924] <TASK> [ 25.078108] unregister_hdlc_device+0x16/0x30 [ 25.078481] slgt_cleanup+0x157/0x9f0 [synclink_gt]
Fix this by checking whether the 'info->netdev' is a null pointer first.
Reviewed-by: Jiri Slaby jirislaby@kernel.org Signed-off-by: Zheyu Ma zheyuma97@gmail.com Link: https://lore.kernel.org/r/20220410114814.3920474-1-zheyuma97@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/synclink_gt.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c index afe34beec720..11c62fcd67f2 100644 --- a/drivers/tty/synclink_gt.c +++ b/drivers/tty/synclink_gt.c @@ -1753,6 +1753,8 @@ static int hdlcdev_init(struct slgt_info *info) */ static void hdlcdev_exit(struct slgt_info *info) { + if (!info->netdev) + return; unregister_hdlc_device(info->netdev); free_netdev(info->netdev); info->netdev = NULL;