From: George Kennedy <george.kennedy@oracle.com>
To: gregkh@linuxfoundation.org, jslaby@suse.cz,
torvalds@linux-foundation.org
Cc: george.kennedy@oracle.com, sfr@canb.auug.org.au,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-serial@vger.kernel.org
Subject: [PATCH] vc_screen: break from vcs_read() while loop if vcs_vc() returns NULL
Date: Mon, 6 Feb 2023 12:34:04 -0500 [thread overview]
Message-ID: <1675704844-17228-1-git-send-email-george.kennedy@oracle.com> (raw)
If vcs_vc() returns NULL in vcs_read(), break if partial read,
else if no reads have been done, go to unlock_out and return ENXIO.
Fixes: 226fae124b2d ("vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
---
drivers/tty/vt/vc_screen.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index f566eb1839dc..29288401cf9e 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -403,10 +403,13 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
unsigned int this_round, skip = 0;
int size;
- ret = -ENXIO;
vc = vcs_vc(inode, &viewed);
- if (!vc)
+ if (!vc) {
+ if (read)
+ break;
+ ret = -ENXIO;
goto unlock_out;
+ }
/* Check whether we are above size each round,
* as copy_to_user at the end of this loop
--
2.31.1
next reply other threads:[~2023-02-06 17:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-06 17:34 George Kennedy [this message]
2023-02-06 18:12 ` [PATCH] vc_screen: break from vcs_read() while loop if vcs_vc() returns NULL Linus Torvalds
2023-02-06 18:20 ` George Kennedy
2023-02-06 18:31 ` Greg KH
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