DPDK patches and discussions
 help / color / mirror / Atom feed
From: Martin Weiser <martin.weiser@allegro-packets.com>
To: Ciara Loftus <ciara.loftus@intel.com>, Qi Zhang <qi.z.zhang@intel.com>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH] net/af_xdp: fix integer overflow in umem size calculation
Date: Thu, 29 Oct 2020 13:41:25 +0100
Message-ID: <c5e85c73-ba24-bbf8-b1c9-9b1656919c61@allegro-packets.com> (raw)
In-Reply-To: <20201029112542.96131-1-martin.weiser@allegro-packets.com>

Hi,

the reason why I stumbled across this issue is because I was getting
inconsistent errors during interface rx queue setup.
We generally use quite large mempools and it looks like the umem setup
fails for larger sizes. But because of the integer overflow the
umem_size sometimes became small enough to let the umem setup work, so
it was not immediately obvious what was going wrong.

It seems that the umem setup (specifically the setsockopt call with
XDP_UMEM_REG in libbpf's xsk_umem__create_v0_0_4()) fails with any
length greater than 2GB and returns ENOMEM. This at least happens on our
systems with kernel 5.8.
Are you aware of any such kernel-side limitation? This basically makes
af_xdp unusable with mempools larger than 2GB.

Best regards,
Martin


Am 29.10.20 um 12:25 schrieb Martin Weiser:
> The multiplication of two u32 integers may cause an overflow with large
> mempool sizes.
>
> Fixes: 74b46340e2d4 ("net/af_xdp: support shared UMEM")
> Cc: ciara.loftus@intel.com
>
> Signed-off-by: Martin Weiser <martin.weiser@allegro-packets.com>
> ---
>  drivers/net/af_xdp/rte_eth_af_xdp.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
> index df2767b81..4076ff797 100644
> --- a/drivers/net/af_xdp/rte_eth_af_xdp.c
> +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
> @@ -968,7 +968,8 @@ xsk_umem_info *xdp_umem_configure(struct pmd_internals *internals,
>  
>  		umem->mb_pool = mb_pool;
>  		base_addr = (void *)get_base_addr(mb_pool, &align);
> -		umem_size = mb_pool->populated_size * usr_config.frame_size +
> +		umem_size = (uint64_t)mb_pool->populated_size *
> +				(uint64_t)usr_config.frame_size +
>  				align;
>  
>  		ret = xsk_umem__create(&umem->umem, base_addr, umem_size,


  reply	other threads:[~2020-10-29 12:41 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-29 11:25 Martin Weiser
2020-10-29 12:41 ` Martin Weiser [this message]
2020-10-30 15:01   ` Ferruh Yigit

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=c5e85c73-ba24-bbf8-b1c9-9b1656919c61@allegro-packets.com \
    --to=martin.weiser@allegro-packets.com \
    --cc=ciara.loftus@intel.com \
    --cc=dev@dpdk.org \
    --cc=qi.z.zhang@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

DPDK patches and discussions

This inbox may be cloned and mirrored by anyone:

	git clone --mirror https://inbox.dpdk.org/dev/0 dev/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dev dev/ https://inbox.dpdk.org/dev \
		dev@dpdk.org
	public-inbox-index dev

Example config snippet for mirrors.
Newsgroup available over NNTP:
	nntp://inbox.dpdk.org/inbox.dpdk.dev


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git