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tty: synclink_gt: Fix null-pointer-dereference in slgt_clean()

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[ Upstream commit 689ca31c54 ]

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>
This commit is contained in:
Zheyu Ma 2022-04-10 19:48:14 +08:00 committed by Greg Kroah-Hartman
parent f00863b470
commit ba08cbc5b5
1 changed files with 2 additions and 0 deletions
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2
drivers/tty/synclink_gt.c
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@ -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;