From: Yonghong Song <yhs@fb.com>
To: YANG LI <abaci-bugfix@linux.alibaba.com>, <ast@kernel.org>
Cc: <daniel@iogearbox.net>, <davem@davemloft.net>, <kuba@kernel.org>,
<hawk@kernel.org>, <john.fastabend@gmail.com>,
<andrii@kernel.org>, <kafai@fb.com>, <songliubraving@fb.com>,
<kpsingh@kernel.org>, <netdev@vger.kernel.org>,
<bpf@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] bpf: fix: address of local auto-variable assigned to a function parameter.
Date: Wed, 23 Dec 2020 23:31:58 -0800 [thread overview]
Message-ID: <bd622b3f-7912-e61d-8101-379ebbdf094f@fb.com> (raw)
In-Reply-To: <1608793298-123684-1-git-send-email-abaci-bugfix@linux.alibaba.com>
On 12/23/20 11:01 PM, YANG LI wrote:
> Assigning local variable txq to the outputting parameter xdp->txq is not
> safe, txq will be released after the end of the function call.
> Then the result of using xdp is unpredictable.
>
> Fix this error by defining the struct xdp_txq_info in function
> dev_map_run_prog() as a static type.
>
> Signed-off-by: YANG LI <abaci-bugfix@linux.alibaba.com>
> Reported-by: Abaci <abaci@linux.alibaba.com>
> ---
> kernel/bpf/devmap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
> index f6e9c68..af6f004 100644
> --- a/kernel/bpf/devmap.c
> +++ b/kernel/bpf/devmap.c
> @@ -454,7 +454,7 @@ static struct xdp_buff *dev_map_run_prog(struct net_device *dev,
> struct xdp_buff *xdp,
> struct bpf_prog *xdp_prog)
> {
> - struct xdp_txq_info txq = { .dev = dev };
> + static struct xdp_txq_info txq = { .dev = dev };
> u32 act;
>
> xdp_set_data_meta_invalid(xdp);
exposing txq outside the routine with 'static' definition is not
a good practice. maybe just reset xdp->txq = NULl right before
function return?
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index f6e9c68afdd4..50f5c20a33a3 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -475,6 +475,7 @@ static struct xdp_buff *dev_map_run_prog(struct
net_device *dev,
}
xdp_return_buff(xdp);
+ xdp->txq = NULL;
return NULL;
}
-bash-4.4$
next prev parent reply other threads:[~2020-12-24 7:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-24 7:01 [PATCH] bpf: fix: address of local auto-variable assigned to a function parameter YANG LI
2020-12-24 7:31 ` Yonghong Song [this message]
2020-12-25 0:49 ` David Ahern
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