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From: Zheyu Ma <zheyuma97@gmail.com>
To: gregkh@linuxfoundation.org, jirislaby@kernel.org
Cc: linux-kernel@vger.kernel.org, Zheyu Ma <zheyuma97@gmail.com>
Subject: [PATCH] tty: synclink_gt: Fix null-pointer-dereference in slgt_clean()
Date: Sun, 10 Apr 2022 19:48:14 +0800	[thread overview]
Message-ID: <20220410114814.3920474-1-zheyuma97@gmail.com> (raw)

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.

Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
---
 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 25c558e65ece..9bc2a9265277 100644
--- a/drivers/tty/synclink_gt.c
+++ b/drivers/tty/synclink_gt.c
@@ -1746,6 +1746,8 @@ 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;
-- 
2.25.1


             reply	other threads:[~2022-04-10 11:55 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-10 11:48 Zheyu Ma [this message]
2022-04-11 10:12 ` [PATCH] tty: synclink_gt: Fix null-pointer-dereference in slgt_clean() Jiri Slaby
2022-04-11 10:46   ` Zheyu Ma

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