Re: [PATCH] cifs: missing null pointer check in cifs_mount

[Steve French <smfrench@gmail.com>]

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updated patch attached with Aurelien's suggestion.

On Wed, Jun 23, 2021 at 7:17 AM Paulo Alcantara <pc@cjr.nz> wrote:
>
> Agreed.
>
> On June 23, 2021 8:48:24 AM GMT-03:00, "Aurélien Aptel" <aaptel@suse.com> wrote:
> >Steve French <smfrench@gmail.com> writes:
> >> We weren't checking if tcon is null before setting dfs path,
> >> although we check for null tcon in an earlier assignment statement.
> >
> >If tcon is NULL there is no point in continuing in that function, we
> >should have exited earlier.
> >
> >If tcon is NULL it means mount_get_conns() failed so presumably rc will
> >be != 0 and we would goto error.
> >
> >I don't think this is needed. We could change the existing check after
> >the loop to this you really want to be safe:
> >
> >       if (rc || !tcon)
> >               goto error;
> >
> >
> >Cheers,



-- 
Thanks,

Steve

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From 162004a2f7ef5c77600e364dc4e9315b0e6ca386 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Wed, 23 Jun 2021 19:32:24 -0500
Subject: [PATCH] cifs: missing null pointer check in cifs_mount

We weren't checking if tcon is null before setting dfs path,
although we check for null tcon in an earlier assignment statement.

Addresses-Coverity: 1476411 ("Dereference after null check")
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/connect.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 8d95607a9312..c8079376d294 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3451,7 +3451,7 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx)
 			rc = -ELOOP;
 	} while (rc == -EREMOTE);
 
-	if (rc)
+	if (rc || !tcon)
 		goto error;
 
 	kfree(ref_path);
-- 
2.30.2