linux-kernel - [PATCH 5.15 101/177] net: stmmac: dwmac-rk: fix oob read in rk_gmac

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Date:   Mon, 20 Dec 2021 15:34:11 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, John Keeping <john@...anate.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 101/177] net: stmmac: dwmac-rk: fix oob read in rk_gmac_setup

From: John Keeping <john@...anate.com>

[ Upstream commit 0546b224cc7717cc8a2db076b0bb069a9c430794 ]

KASAN reports an out-of-bounds read in rk_gmac_setup on the line:

	while (ops->regs[i]) {

This happens for most platforms since the regs flexible array member is
empty, so the memory after the ops structure is being read here.  It
seems that mostly this happens to contain zero anyway, so we get lucky
and everything still works.

To avoid adding redundant data to nearly all the ops structures, add a
new flag to indicate whether the regs field is valid and avoid this loop
when it is not.

Fixes: 3bb3d6b1c195 ("net: stmmac: Add RK3566/RK3568 SoC support")
Signed-off-by: John Keeping <john@...anate.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
index 6924a6aacbd53..c469abc91fa1b 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
@@ -33,6 +33,7 @@ struct rk_gmac_ops {
 	void (*set_rgmii_speed)(struct rk_priv_data *bsp_priv, int speed);
 	void (*set_rmii_speed)(struct rk_priv_data *bsp_priv, int speed);
 	void (*integrated_phy_powerup)(struct rk_priv_data *bsp_priv);
+	bool regs_valid;
 	u32 regs[];
 };
 
@@ -1092,6 +1093,7 @@ static const struct rk_gmac_ops rk3568_ops = {
 	.set_to_rmii = rk3568_set_to_rmii,
 	.set_rgmii_speed = rk3568_set_gmac_speed,
 	.set_rmii_speed = rk3568_set_gmac_speed,
+	.regs_valid = true,
 	.regs = {
 		0xfe2a0000, /* gmac0 */
 		0xfe010000, /* gmac1 */
@@ -1383,7 +1385,7 @@ static struct rk_priv_data *rk_gmac_setup(struct platform_device *pdev,
 	 * to be distinguished.
 	 */
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (res) {
+	if (res && ops->regs_valid) {
 		int i = 0;
 
 		while (ops->regs[i]) {
-- 
2.33.0