linux-kernel - [PATCH] tty: fix memory leak in vc

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Date:   Sun, 28 Mar 2021 00:44:43 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     gregkh@...uxfoundation.org, jirislaby@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Pavel Skripkin <paskripkin@...il.com>,
        syzbot+bcc922b19ccc64240b42@...kaller.appspotmail.com
Subject: [PATCH] tty: fix memory leak in vc_deallocate

syzbot reported memory leak in tty/vt.
The problem was in VT_DISALLOCATE ioctl cmd.
After allocating unimap with PIO_UNIMAP it wasn't
freed via VT_DISALLOCATE, but vc_cons[currcons].d was
zeroed.

Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
Reported-by: syzbot+bcc922b19ccc64240b42@...kaller.appspotmail.com
---
 drivers/tty/vt/vt.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 284b07224c55..0cc360da5426 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -1381,6 +1381,7 @@ struct vc_data *vc_deallocate(unsigned int currcons)
 		atomic_notifier_call_chain(&vt_notifier_list, VT_DEALLOCATE, &param);
 		vcs_remove_sysfs(currcons);
 		visual_deinit(vc);
+		con_free_unimap(vc);
 		put_pid(vc->vt_pid);
 		vc_uniscr_set(vc, NULL);
 		kfree(vc->vc_screenbuf);
-- 
2.30.2