APPLIED/cmt: [PATCH SRU E/D/B] xfrm: Fix memleak on xfrm state destroy

[Khaled Elmously]

The patch didn't apply cleanly to Bionic. The affected function was called xfrm_state_gc_destroy() in Bionic (not ___xfrm_state_destroy()). 

I updated the patch for Bionic accordingly.

On 2019-11-29 13:05:39 , Stefan Bader wrote:
> From: Steffen Klassert <steffen.klassert at secunet.com>
> 
> We leak the page that we use to create skb page fragments
> when destroying the xfrm_state. Fix this by dropping a
> page reference if a page was assigned to the xfrm_state.
> 
> Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
> Reported-by: JD <jdtxs00 at gmail.com>
> Reported-by: Paul Wouters <paul at nohats.ca>
> Signed-off-by: Steffen Klassert <steffen.klassert at secunet.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1853197
> 
> (cherry picked from commit 86c6739eda7d2a03f2db30cbee67a5fb81afa8ba)
> Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
> ---
> 
> This fixes a memory leak which appears to loose 8 pages for each ipsec
> connection that is done. Issue was introduced in v4.11 and fixed in v5.4
> so unstable should have it.
> 
> Needs -C2 to apply to Bionic [build-tested in Bionic, too].
> 
>  net/xfrm/xfrm_state.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
> index c6f3c4a1bd99..f3423562d933 100644
> --- a/net/xfrm/xfrm_state.c
> +++ b/net/xfrm/xfrm_state.c
> @@ -495,6 +495,8 @@ static void ___xfrm_state_destroy(struct xfrm_state *x)
>  		x->type->destructor(x);
>  		xfrm_put_type(x->type);
>  	}
> +	if (x->xfrag.page)
> +		put_page(x->xfrag.page);
>  	xfrm_dev_state_free(x);
>  	security_xfrm_state_free(x);
>  	xfrm_state_free(x);
> -- 
> 2.17.1
> 
> 
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