[PATCH] aoe: fix the potential use-after-free problem in more places

["Lee, Chun-Yi" <joeyli.kernel@xxxxxxxxx>]

From: Chun-Yi Lee <jlee@xxxxxxxx>

For fixing CVE-2023-6270, f98364e92662 ("aoe: fix the potential
use-after-free problem in aoecmd_cfg_pkts") make tx() do dev_put()
instead of doing in aoecmd_cfg_pkts(). It avoids that the tx() runs
into use-after-free.

But Nicolai Stange found more places in aoe have potential use-after-free
problem with tx(). e.g. revalidate(), aoecmd_ata_rw(), resend(), probe()
and aoecmd_cfg_rsp(). Those functions also use aoenet_xmit() to push
packet to tx queue. So they should also use dev_hold() to increase the
refcnt of skb->dev.

This patch adds dev_hold() to those functions and also uses dev_put()
when the skb_clone() returns NULL.

v2:
- Base on submitting-patches.rst document to improve patch description.
- Used curly brackets in the if-else blocks.

Link: https://nvd.nist.gov/vuln/detail/CVE-2023-6270
Fixes: f98364e92662 ("aoe: fix the potential use-after-free problem in aoecmd_cfg_pkts")
Reported-by: Nicolai Stange <nstange@xxxxxxxx>
Signed-off-by: Chun-Yi Lee <jlee@xxxxxxxx>
---
 drivers/block/aoe/aoecmd.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c
index cc9077b588d7..d1f4ddc57645 100644
--- a/drivers/block/aoe/aoecmd.c
+++ b/drivers/block/aoe/aoecmd.c
@@ -361,6 +361,7 @@ ata_rw_frameinit(struct frame *f)
 	}
 
 	ah->cmdstat = ATA_CMD_PIO_READ | writebit | extbit;
+	dev_hold(t->ifp->nd);
 	skb->dev = t->ifp->nd;
 }
 
@@ -401,6 +402,8 @@ aoecmd_ata_rw(struct aoedev *d)
 		__skb_queue_head_init(&queue);
 		__skb_queue_tail(&queue, skb);
 		aoenet_xmit(&queue);
+	} else {
+		dev_put(f->t->ifp->nd);
 	}
 	return 1;
 }
@@ -483,10 +486,13 @@ resend(struct aoedev *d, struct frame *f)
 	memcpy(h->dst, t->addr, sizeof h->dst);
 	memcpy(h->src, t->ifp->nd->dev_addr, sizeof h->src);
 
+	dev_hold(t->ifp->nd);
 	skb->dev = t->ifp->nd;
 	skb = skb_clone(skb, GFP_ATOMIC);
-	if (skb == NULL)
+	if (skb == NULL) {
+		dev_put(t->ifp->nd);
 		return;
+	}
 	f->sent = ktime_get();
 	__skb_queue_head_init(&queue);
 	__skb_queue_tail(&queue, skb);
@@ -617,6 +623,8 @@ probe(struct aoetgt *t)
 		__skb_queue_head_init(&queue);
 		__skb_queue_tail(&queue, skb);
 		aoenet_xmit(&queue);
+	} else {
+		dev_put(f->t->ifp->nd);
 	}
 }
 
@@ -1395,6 +1403,7 @@ aoecmd_ata_id(struct aoedev *d)
 	ah->cmdstat = ATA_CMD_ID_ATA;
 	ah->lba3 = 0xa0;
 
+	dev_hold(t->ifp->nd);
 	skb->dev = t->ifp->nd;
 
 	d->rttavg = RTTAVG_INIT;
@@ -1404,6 +1413,8 @@ aoecmd_ata_id(struct aoedev *d)
 	skb = skb_clone(skb, GFP_ATOMIC);
 	if (skb)
 		f->sent = ktime_get();
+	else
+		dev_put(t->ifp->nd);
 
 	return skb;
 }
-- 
2.35.3