linux-kernel - Re: [PATCH] nfs: Added pointer check

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Date:   Wed, 16 Nov 2022 15:10:06 +0000
From:   Trond Myklebust <trondmy@...merspace.com>
To:     Denis Arefev <arefev@...mel.ru>
CC:     Trond Myklebust <trondmy@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "trufanov@...mel.ru" <trufanov@...mel.ru>,
        "vfh@...mel.ru" <vfh@...mel.ru>
Subject: Re: [PATCH] nfs: Added pointer check



> On Nov 16, 2022, at 07:15, Denis Arefev <arefev@...mel.ru> wrote:
> 
> [You don't often get email from arefev@...mel.ru. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> 
> Return value of a function 'xdr_inline_decode' is dereferenced at
> nfs4xdr.c:5540 without checking for null,
> ut it is usually checked for this function
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Signed-off-by: Denis Arefev <arefev@...mel.ru>
> ---
> fs/nfs/nfs4xdr.c | 2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> index c6dbfcae7517..571cc63ecb61 100644
> --- a/fs/nfs/nfs4xdr.c
> +++ b/fs/nfs/nfs4xdr.c
> @@ -5533,6 +5533,8 @@ static int decode_op_map(struct xdr_stream *xdr, struct nfs4_op_map *op_map)
>        if (bitmap_words > NFS4_OP_MAP_NUM_WORDS)
>                return -EIO;
>        p = xdr_inline_decode(xdr, 4 * bitmap_words);
> +       if (!p)
> +               return -EIO;
>        for (i = 0; i < bitmap_words; i++)
>                op_map->u.words[i] = be32_to_cpup(p++);
> 

This bug was fixed in Linux 5.16 and newer by commit f114759c322e ("NFSv4: Fix potential Oops in decode_op_map()”).

_________________________________
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@...merspace.com