[PATCH] Prevent out-of-bounds read/write in bcmasp_netfilt_rd and bcmasp_netfilt_wr

From: Yuran Pereira <yuran.pereira@hotmail.com>
To: davem@davemloft.net, netdev@vger.kernel.org
Cc: Yuran Pereira <yuran.pereira@hotmail.com>,
	florian.fainelli@broadcom.com, linux-kernel@vger.kernel.org,
	justin.chen@broadcom.com, edumazet@google.com,
	bcm-kernel-feedback-list@broadcom.com, kuba@kernel.org,
	pabeni@redhat.com,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: [PATCH] Prevent out-of-bounds read/write in bcmasp_netfilt_rd and bcmasp_netfilt_wr
Date: Fri,  3 Nov 2023 17:57:48 +0530	[thread overview]
Message-ID: <DB3PR10MB6835E073F668AD24F57AE64AE8A5A@DB3PR10MB6835.EURPRD10.PROD.OUTLOOK.COM> (raw)

The functions `bcmasp_netfilt_rd` and `bcmasp_netfilt_wr` both call
`bcmasp_netfilt_get_reg_offset` which, when it fails, returns `-EINVAL`.
This could lead to an out-of-bounds read or write when `rx_filter_core_rl`
or `rx_filter_core_wl` is called.

This patch adds a check in both functions to return immediately if
`bcmasp_netfilt_get_reg_offset` fails. This prevents potential out-of-bounds read
or writes, and ensures that no undefined or buggy behavior would originate from
the failure of `bcmasp_netfilt_get_reg_offset`.

Addresses-Coverity-IDs: 1544536 ("Out-of-bounds access")
Signed-off-by: Yuran Pereira <yuran.pereira@hotmail.com>
---
 drivers/net/ethernet/broadcom/asp2/bcmasp.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/asp2/bcmasp.c b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
index 29b04a274d07..8b90b761bdec 100644
--- a/drivers/net/ethernet/broadcom/asp2/bcmasp.c
+++ b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
@@ -227,6 +227,8 @@ static void bcmasp_netfilt_wr(struct bcmasp_priv *priv,
 
 	reg_offset = bcmasp_netfilt_get_reg_offset(priv, nfilt, reg_type,
 						   offset);
+	if (reg_offset < 0)
+		return;
 
 	rx_filter_core_wl(priv, val, reg_offset);
 }
@@ -244,6 +246,8 @@ static u32 bcmasp_netfilt_rd(struct bcmasp_priv *priv,
 
 	reg_offset = bcmasp_netfilt_get_reg_offset(priv, nfilt, reg_type,
 						   offset);
+	if (reg_offset < 0)
+		return 0;
 
 	return rx_filter_core_rl(priv, reg_offset);
 }
-- 
2.25.1

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