• Arnd Bergmann's avatar
    media: cxd2880-spi: avoid out-of-bounds access warning · 53dcd70e
    Arnd Bergmann authored
    The -Warray-bounds warning in gcc-8 triggers for a newly added file:
    
    drivers/media/spi/cxd2880-spi.c: In function 'cxd2880_write_reg':
    drivers/media/spi/cxd2880-spi.c:111:3: error: 'memcpy' forming offset [133, 258] is out of the bounds [0, 132] of object 'send_data' with type 'u8[132]' {aka 'unsigned char[132]'} [-Werror=array-bounds]
    
    The problem appears to be that we have two range checks in this function,
    first comparing against BURST_WRITE_MAX (128) and then comparing against
    a literal '255'. The logic checking the buffer size looks at the second
    one and decides that this might be the actual maximum data length.
    
    This is understandable behavior from the compiler, but the code is actually
    safe. Since the first check is already shorter, we can remove the loop
    and only leave that. To be on the safe side in case BURST_WRITE_MAX might
    be increased, I'm leaving the check against U8_MAX.
    
    Fixes: bd24fcdd ("media: cxd2880-spi: Add support for CXD2880 SPI interface")
    
    Cc: Martin Sebor <msebor@gmail.com>
    Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
    Reviewed-by: default avatarYasunari Takiguchi <Yasunari.Takiguchi@sony.com>
    Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
    53dcd70e
cxd2880-spi.c 14.4 KB