[lustre-devel] [PATCH v2] staging/lustre/ptlrpc: Removes potential null dereference

[James Simmons]

> This looks wrong - You return -EINVAL from sptlrpc_pack_user_desc, but then
> the caller checks "!desc".  Desc will not be null, since you've returned
> -EINVAL.

Actually 'if (!desc)' is equal to 'if (desc != 0). Yes it can be confusing.
I recommend 'if (desc < 0)' instead to make it clearer what is being 
tested for.

> - Patrick
> 
> On 05/16/2016 09:17 AM, Lidza Louina wrote:
> > The lustre_msg_buf method could return NULL. Subsequent code didn't
> > check if it's null before using it. This patch adds two checks.
> >
> > Signed-off-by: Lidza Louina <lidza.louina at oracle.com>
> > ---
> >   drivers/staging/lustre/lustre/ptlrpc/sec.c       | 2 ++
> >   drivers/staging/lustre/lustre/ptlrpc/sec_plain.c | 9 +++++++--
> >   2 files changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/staging/lustre/lustre/ptlrpc/sec.c
> > b/drivers/staging/lustre/lustre/ptlrpc/sec.c
> > index 187fd1d..e6fedc3 100644
> > --- a/drivers/staging/lustre/lustre/ptlrpc/sec.c
> > +++ b/drivers/staging/lustre/lustre/ptlrpc/sec.c
> > @@ -2195,6 +2195,8 @@ int sptlrpc_pack_user_desc(struct lustre_msg *msg, int
> > offset)
> >    struct ptlrpc_user_desc *pud;
> >   
> >   	pud = lustre_msg_buf(msg, offset, 0);
> > +	if (!pud)
> > +		return -EINVAL;
> >   
> >    pud->pud_uid = from_kuid(&init_user_ns, current_uid());
> >    pud->pud_gid = from_kgid(&init_user_ns, current_gid());
> > diff --git a/drivers/staging/lustre/lustre/ptlrpc/sec_plain.c
> > b/drivers/staging/lustre/lustre/ptlrpc/sec_plain.c
> > index 37c9f4c..51741c8 100644
> > --- a/drivers/staging/lustre/lustre/ptlrpc/sec_plain.c
> > +++ b/drivers/staging/lustre/lustre/ptlrpc/sec_plain.c
> > @@ -542,6 +542,7 @@ int plain_alloc_reqbuf(struct ptlrpc_sec *sec,
> >   {
> >    __u32 buflens[PLAIN_PACK_SEGMENTS] = { 0, };
> >    int alloc_len;
> > +	int desc;
> >   
> >    buflens[PLAIN_PACK_HDR_OFF] = sizeof(struct plain_header);
> >    buflens[PLAIN_PACK_MSG_OFF] = msgsize;
> > @@ -574,8 +575,12 @@ int plain_alloc_reqbuf(struct ptlrpc_sec *sec,
> >    lustre_init_msg_v2(req->rq_reqbuf, PLAIN_PACK_SEGMENTS, buflens, NULL);
> >    req->rq_reqmsg = lustre_msg_buf(req->rq_reqbuf, PLAIN_PACK_MSG_OFF, 0);
> >   -	if (req->rq_pack_udesc)
> > -		sptlrpc_pack_user_desc(req->rq_reqbuf, PLAIN_PACK_USER_OFF);
> > +	if (req->rq_pack_udesc) {
> > +		desc = sptlrpc_pack_user_desc(req->rq_reqbuf,
> > +					      PLAIN_PACK_USER_OFF);
> > +		if (!desc)
> > +			return desc;
> > +	}
> >   
> >   	return 0;
> >   }
> 
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