On Thu, 2020-01-16 at 20:18 -0600, Benjamin Marzinski wrote:
> If do_inq returns a page with a length that is less than maxlen, but
> larger than DEFAULT_SGIO_LEN, this function will loop forever. Also
> if do_inq returns with a length equal to or greater than maxlen,
> sgio_get_vpd will exit immediately, even if it hasn't read the entire
> page. Fix these issues, modify the tests to verify the new behavior.
>
> Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
> ---
> libmultipath/discovery.c | 12 +++---
> tests/vpd.c | 84 ++++++++++++++++++++++++------------
> ----
> 2 files changed, 57 insertions(+), 39 deletions(-)
>
> diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
> index 72f455e8..3c72a80a 100644
> --- a/libmultipath/discovery.c
> +++ b/libmultipath/discovery.c
> @@ -870,6 +870,7 @@ static int
> sgio_get_vpd (unsigned char * buff, int maxlen, int fd, int pg)
> {
> int len = DEFAULT_SGIO_LEN;
> + int rlen;
>
> if (fd < 0) {
> errno = EBADF;
> @@ -877,12 +878,11 @@ sgio_get_vpd (unsigned char * buff, int maxlen,
> int fd, int pg)
> }
> retry:
> if (0 == do_inq(fd, 0, 1, pg, buff, len)) {
> - len = get_unaligned_be16(&buff[2]) + 4;
> - if (len >= maxlen)
> - return len;
> - if (len > DEFAULT_SGIO_LEN)
> - goto retry;
> - return len;
> + rlen = get_unaligned_be16(&buff[2]) + 4;
> + if (rlen <= len || len >= maxlen)
> + return rlen;
> + len = (rlen < maxlen)? rlen : maxlen;
> + goto retry;
> }
> return -1;
> }
This looks good.
> diff --git a/tests/vpd.c b/tests/vpd.c
> index d9f80eaa..4dbce010 100644
> --- a/tests/vpd.c
> +++ b/tests/vpd.c
> @@ -306,7 +306,7 @@ static int create_vpd83(unsigned char *buf,
> size_t bufsiz, const char *id,
> default:
> break;
> }
> - put_unaligned_be16(n, buf + 2);
> + put_unaligned_be16(bufsiz, buf + 2);
> return n + 4;
> }
I can see that you are trying to create a VPD with a certain given
length. But this way you intentionally create a VPD that doesn't
conform to the spec (offset 2 should contain the real length of the
designator list, not some arbitrary value). This is dangerous, in the
future someone may copy this code thinking that it creates a valid
VPD. At least you should add a big fat comment. Better even, you
should leave out this hunk and override the length value in the
actual test (make_test_vpd_eui) if (sml == 1) (and also add a comment).
Regards
Martin
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