Re: [PATCH] scsi: Silence gcc warning

[Philippe Mathieu-Daudé]

On 2/9/21 4:23 PM, Eric Blake wrote:
> On Fedora 33, gcc 10.2.1 notes that scsi_cdb_length(buf) can set
> len==-1, which in turn overflows g_malloc():
> 
> [5/5] Linking target qemu-system-x86_64
> In function ‘scsi_disk_new_request_dump’,
>     inlined from ‘scsi_new_request’ at ../hw/scsi/scsi-disk.c:2608:9:
> ../hw/scsi/scsi-disk.c:2582:19: warning: argument 1 value 
> ‘18446744073709551612’ exceeds maximum object size 9223372036854775807 
> [-Walloc-size-larger-than=]
>  2582 |     line_buffer = g_malloc(len * 5 + 1);
>       |                   ^
> 
> Silence it with a decent assertion, since we only convert a buffer to
> bytes when we have a valid cdb length.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  hw/scsi/scsi-disk.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index ed52fcd49ff0..b3311a5657b7 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -2579,6 +2579,7 @@ static void scsi_disk_new_request_dump(uint32_t lun, 
> uint32_t tag, uint8_t *buf)
>      int len = scsi_cdb_length(buf);
>      char *line_buffer, *p;
> 
> +    assert(len > 0 && len <= 16);
>      line_buffer = g_malloc(len * 5 + 1);
> 
>      for (i = 0, p = line_buffer; i < len; i++) {
> 

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>