• Dan Carpenter's avatar
    media: pvrusb2: Prevent a buffer overflow · 5f67ca2a
    Dan Carpenter authored
    [ Upstream commit c1ced46c ]
    
    The ctrl_check_input() function is called from pvr2_ctrl_range_check().
    It's supposed to validate user supplied input and return true or false
    depending on whether the input is valid or not.  The problem is that
    negative shifts or shifts greater than 31 are undefined in C.  In
    practice with GCC they result in shift wrapping so this function returns
    true for some inputs which are not valid and this could result in a
    buffer overflow:
    
        drivers/media/usb/pvrusb2/pvrusb2-ctrl.c:205 pvr2_ctrl_get_valname()
        warn: uncapped user index 'names[val]'
    
    The cptr->hdw->input_allowed_mask mask is configured in pvr2_hdw_create()
    and the highest valid bit is BIT(4).
    
    Fixes: 7fb20fa3 ("V4L/DVB (7299): pvrusb2: Improve logic which handles input choice availability")
    Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
    Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
    Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
    Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
    5f67ca2a
pvrusb2-hdw.h 12 KB