lkml.org 
[lkml]   [2020]   [Dec]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH] bpf: fix: address of local auto-variable assigned to a function parameter.
From
Date


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$
\
 
 \ /
  Last update: 2020-12-24 08:35    [W:0.051 / U:0.432 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site