Re: [PATCH] snic: correctly check for array overrun on overly long version number

Ewan Milne
2016-03-01T17:29:41Z

On Thu, 2016-02-25 at 22:58 +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> The snic version number is expected to be 4 decimals in the form like
> a netmask string with each number stored in an element in array v.
> However, there is an off-by-one check on the number of elements in v
> allowing one to pass a 5 decimal version number causing v[4] to be
> referenced, causing a buffer overrun. Fix the off-by-one error by
> comparing to i > 3 rather than 4.
>
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
> drivers/scsi/snic/snic_ctl.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/snic/snic_ctl.c b/drivers/scsi/snic/snic_ctl.c
> index aebe753..ab0e06b 100644
> --- a/drivers/scsi/snic/snic_ctl.c
> +++ b/drivers/scsi/snic/snic_ctl.c
> @@ -75,7 +75,7 @@ snic_ver_enc(const char *s)
> continue;
> }
>
> - if (i > 4 || !isdigit(c))
> + if (i > 3 || !isdigit(c))
> goto end;
>
> v[i] = v[i] * 10 + (c - '0');

int v[4] = {0};

So clearly the i > 4 test is wrong and should be i > 3.

Reviewed-by: Ewan D. Milne <emilne@redhat.com>