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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Felicitas Hetzelt <felicitashetzelt@gmail.com>,
        Jacob Keller <jacob.e.keller@intel.com>,
        Tony Nguyen <anthony.l.nguyen@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.14 109/172] e100: fix length calculation in e100_get_regs_len
Date:   Mon,  4 Oct 2021 14:52:39 +0200
Message-Id: <20211004125048.501036388@linuxfoundation.org>
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From: Jacob Keller <jacob.e.keller@intel.com>

[ Upstream commit 4329c8dc110b25d5f04ed20c6821bb60deff279f ]

commit abf9b902059f ("e100: cleanup unneeded math") tried to simplify
e100_get_regs_len and remove a double 'divide and then multiply'
calculation that the e100_reg_regs_len function did.

This change broke the size calculation entirely as it failed to account
for the fact that the numbered registers are actually 4 bytes wide and
not 1 byte. This resulted in a significant under allocation of the
register buffer used by e100_get_regs.

Fix this by properly multiplying the register count by u32 first before
adding the size of the dump buffer.

Fixes: abf9b902059f ("e100: cleanup unneeded math")
Reported-by: Felicitas Hetzelt <felicitashetzelt@gmail.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/intel/e100.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/e100.c b/drivers/net/ethernet/intel/e100.c
index 1b0958bd24f6..71b9f0563b32 100644
--- a/drivers/net/ethernet/intel/e100.c
+++ b/drivers/net/ethernet/intel/e100.c
@@ -2441,7 +2441,11 @@ static void e100_get_drvinfo(struct net_device *netdev,
 static int e100_get_regs_len(struct net_device *netdev)
 {
 	struct nic *nic = netdev_priv(netdev);
-	return 1 + E100_PHY_REGS + sizeof(nic->mem->dump_buf);
+
+	/* We know the number of registers, and the size of the dump buffer.
+	 * Calculate the total size in bytes.
+	 */
+	return (1 + E100_PHY_REGS) * sizeof(u32) + sizeof(nic->mem->dump_buf);
 }
 
 static void e100_get_regs(struct net_device *netdev,
-- 
2.33.0