linux-kernel - qla3xxx: u32 constant overflow in fm93c56a

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Date:   Sun, 15 Jan 2017 13:03:45 +0100
From:   Nicolas Iooss <nicolas.iooss_linux@....org>
To:     Dept-GELinuxNICDev@...ium.com, netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: qla3xxx: u32 constant overflow in fm93c56a_select()

Hello,

In drivers/net/ethernet/qlogic/qla3xxx.c, fm93c56a_select() currently calls:

  ql_write_nvram_reg(qdev, spir,
    ((ISP_NVRAM_MASK << 16) | qdev->eeprom_cmd_data));

and ISP_NVRAM_MASK is defined as (0x000F << 16).

ql_write_nvram_reg() writes a 32-bit value but (ISP_NVRAM_MASK << 16)
expands to ((0x000F << 16) << 16) = 0xF << 32, which overflows the u32
type. This means the above call is equivalent to:

  ql_write_nvram_reg(qdev, spir, qdev->eeprom_cmd_data);

Is this something normal, in which case (ISP_NVRAM_MASK << 16) would be
removed, or a bug?

Thanks,
Nicolas