[PATCH] octeontx2-af: Fix use of uninitialized pointer bmap

[PATCH] octeontx2-af: Fix use of uninitialized pointer bmap

[Dinghao Liu]

If req->ctype does not match any of NIX_AQ_CTYPE_CQ,
NIX_AQ_CTYPE_SQ or NIX_AQ_CTYPE_RQ, pointer bmap will remain
uninitialized and be accessed in test_bit(), which can lead
to kernal crash.

Fix this by returning an error code if this case is triggered.

Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
---
 drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c
index 36953d4f51c7..20a64ed24474 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c
@@ -869,19 +869,18 @@ static int nix_lf_hwctx_disable(struct rvu *rvu, struct hwctx_disable_req *req)
 		aq_req.cq_mask.bp_ena = 1;
 		q_cnt = pfvf->cq_ctx->qsize;
 		bmap = pfvf->cq_bmap;
-	}
-	if (req->ctype == NIX_AQ_CTYPE_SQ) {
+	} else if (req->ctype == NIX_AQ_CTYPE_SQ) {
 		aq_req.sq.ena = 0;
 		aq_req.sq_mask.ena = 1;
 		q_cnt = pfvf->sq_ctx->qsize;
 		bmap = pfvf->sq_bmap;
-	}
-	if (req->ctype == NIX_AQ_CTYPE_RQ) {
+	} else if (req->ctype == NIX_AQ_CTYPE_RQ) {
 		aq_req.rq.ena = 0;
 		aq_req.rq_mask.ena = 1;
 		q_cnt = pfvf->rq_ctx->qsize;
 		bmap = pfvf->rq_bmap;
-	}
+	} else
+		return NIX_AF_ERR_AQ_ENQUEUE;
 
 	aq_req.ctype = req->ctype;
 	aq_req.op = NIX_AQ_INSTOP_WRITE;
-- 
2.17.1

Re: [PATCH] octeontx2-af: Fix use of uninitialized pointer bmap

[David Miller]

From: Dinghao Liu <dinghao.liu@zju.edu.cn>
Date: Fri, 24 Jul 2020 16:06:57 +0800

> If req->ctype does not match any of NIX_AQ_CTYPE_CQ,
> NIX_AQ_CTYPE_SQ or NIX_AQ_CTYPE_RQ, pointer bmap will remain
> uninitialized and be accessed in test_bit(), which can lead
> to kernal crash.

This can never happen.

> Fix this by returning an error code if this case is triggered.
> 
> Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>

I strongly dislike changes like this.

Most callers of nix_lf_hwctx_disable() inside of rvu_nix.c set
req->ctype to one of the handled values.

The only other case, rvu_mbox_handler_nix_hwctx_disable(), is a
completely unused function and should be removed.

There is no functional problem in this code at all.

It is not possible show a code path where the stated problem can
actually occur.

Re: Re: [PATCH] octeontx2-af: Fix use of uninitialized pointer bmap

[dinghao.liu]

> From: Dinghao Liu <dinghao.liu@zju.edu.cn>
> Date: Fri, 24 Jul 2020 16:06:57 +0800
> 
> > If req->ctype does not match any of NIX_AQ_CTYPE_CQ,
> > NIX_AQ_CTYPE_SQ or NIX_AQ_CTYPE_RQ, pointer bmap will remain
> > uninitialized and be accessed in test_bit(), which can lead
> > to kernal crash.
> 
> This can never happen.
> 
> > Fix this by returning an error code if this case is triggered.
> > 
> > Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
> 
> I strongly dislike changes like this.
> 
> Most callers of nix_lf_hwctx_disable() inside of rvu_nix.c set
> req->ctype to one of the handled values.
> 
> The only other case, rvu_mbox_handler_nix_hwctx_disable(), is a
> completely unused function and should be removed.
> 
> There is no functional problem in this code at all.
> 
> It is not possible show a code path where the stated problem can
> actually occur.

It's clear to me now. Thanks.

Regards,
Dinghao