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From: David Marchand <david.marchand@redhat.com>
To: Bing Zhao <bingz@mellanox.com>
Cc: "Burakov, Anatoly" <anatoly.burakov@intel.com>,
	Thomas Monjalon <thomas@monjalon.net>, dev <dev@dpdk.org>,
	 dpdk stable <stable@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v3] mem: fix the alloc size roundup overflow
Date: Mon, 11 May 2020 16:52:51 +0200	[thread overview]
Message-ID: <CAJFAV8wbwRhk_ctC8Lxnzg6VCrfRxy9N44eQq0NMQayuDb_jvg@mail.gmail.com> (raw)
In-Reply-To: <1588838574-361500-1-git-send-email-bingz@mellanox.com>

On Thu, May 7, 2020 at 10:03 AM Bing Zhao <bingz@mellanox.com> wrote:
>
> The size checking is done in the caller. The size parameter is an
> unsigned (64b wide) right now, so the comparison with zero should be
> enough in most cases. But it won't help in the following case.
> If the allocating request input a huge number by mistake, e.g., some
> overflow after the calculation (especially subtraction), the checking
> in the caller will succeed since it is not zero. Indeed, there is not
> enough space in the system to support such huge memory allocation.
> Usually it will return failure in the following code. But if the
> input size is just a little smaller than the UINT64_MAX, like -2 in
> signed type.
> The roundup will cause an overflow and then "reset" the size to 0,
> and then only a header (128B now) with zero length will be returned.
> The following will be the previous allocation header.
> It should be OK in most cases if the application won't access the
> memory body. Or else, some critical issue will be caused and not easy
> to debug. So this issue should be prevented at the beginning, like
> other big size failure, NULL pointer should be returned also.
>
> Fixes: fdf20fa7bee9 ("add prefix to cache line macros")
> Cc: stable@dpdk.org
>
> Signed-off-by: Bing Zhao <bingz@mellanox.com>

Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>

Applied, thanks.


-- 
David Marchand


  reply	other threads:[~2020-05-11 14:53 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-07 10:46 [dpdk-dev] [PATCH] " Bing Zhao
2020-04-20 11:39 ` Burakov, Anatoly
2020-04-21  3:18   ` Bing Zhao
2020-05-06 21:43     ` [dpdk-dev] [dpdk-stable] " Thomas Monjalon
2020-05-07  7:39 ` [dpdk-dev] [PATCH v2] " Bing Zhao
2020-05-07  7:41 ` Bing Zhao
2020-05-07  8:02   ` [dpdk-dev] [PATCH v3] " Bing Zhao
2020-05-11 14:52     ` David Marchand [this message]
2020-05-07 11:55   ` [dpdk-dev] [PATCH v2] " Burakov, Anatoly
2020-05-07 12:12     ` [dpdk-dev] [dpdk-stable] " David Marchand
2020-05-07 12:16       ` Bing Zhao
2020-05-07 12:18         ` David Marchand

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