linux-kernel - [PATCH] net: ethernet: ti: cpsw_ale: Fix access to un-initialized memory

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Date:   Mon,  8 Nov 2021 22:28:55 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     grygorii.strashko@...com, davem@...emloft.net, kuba@...nel.org,
        shenyang39@...wei.com, vigneshr@...com
Cc:     linux-omap@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] net: ethernet: ti: cpsw_ale: Fix access to un-initialized memory

It is spurious to allocate a bitmap without initializing it.
So, better safe than sorry, initialize it to 0 at least to have some known
values.

While at it, switch to the devm_bitmap_ API which is less verbose.

Fixes: 4b41d3436796 ("net: ethernet: ti: cpsw: allow untagged traffic on host port")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
Maybe this patch is useless, because of some _add_vlan _del_vlan stuff that
initialize things correctly before they are used, but it really looks
spurious to me.
IIUC, cpsw_rx_vlan_encap() (and the embedded cpsw_ale_get_vlan_p0_untag()
could test any bit in the un-initialized bitmap)

Just a guess, I've not tried to understand all the logic involved.
---
 drivers/net/ethernet/ti/cpsw_ale.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/ti/cpsw_ale.c b/drivers/net/ethernet/ti/cpsw_ale.c
index 0c75e0576ee1..1ef0aaef5c61 100644
--- a/drivers/net/ethernet/ti/cpsw_ale.c
+++ b/drivers/net/ethernet/ti/cpsw_ale.c
@@ -1299,10 +1299,8 @@ struct cpsw_ale *cpsw_ale_create(struct cpsw_ale_params *params)
 	if (!ale)
 		return ERR_PTR(-ENOMEM);
 
-	ale->p0_untag_vid_mask =
-		devm_kmalloc_array(params->dev, BITS_TO_LONGS(VLAN_N_VID),
-				   sizeof(unsigned long),
-				   GFP_KERNEL);
+	ale->p0_untag_vid_mask = devm_bitmap_zalloc(params->dev, VLAN_N_VID,
+						    GFP_KERNEL);
 	if (!ale->p0_untag_vid_mask)
 		return ERR_PTR(-ENOMEM);
 
-- 
2.30.2