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Date: Wed, 6 Mar 2024 19:09:58 +0000
From: Dragos Tatulea <dtatulea@...dia.com>
To: "davem@...emloft.net" <davem@...emloft.net>, "herbert@...dor.apana.org.au"
	<herbert@...dor.apana.org.au>, "dsahern@...nel.org" <dsahern@...nel.org>,
	"steffen.klassert@...unet.com" <steffen.klassert@...unet.com>,
	"pabeni@...hat.com" <pabeni@...hat.com>, "kuba@...nel.org" <kuba@...nel.org>,
	"edumazet@...gle.com" <edumazet@...gle.com>, "almasrymina@...gle.com"
	<almasrymina@...gle.com>
CC: Leon Romanovsky <leonro@...dia.com>, Gal Pressman <gal@...dia.com>,
	"Anatoli.Chechelnickiy@...nterpipe.biz"
	<Anatoli.Chechelnickiy@...nterpipe.biz>, "ian.kumlien@...il.com"
	<ian.kumlien@...il.com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v2] net: esp: fix bad handling of pages from page_pool

On Wed, 2024-03-06 at 21:08 +0200, Dragos Tatulea wrote:
> When the skb is reorganized during esp_output (!esp->inline), the pages
> coming from the original skb fragments are supposed to be released back
> to the system through put_page. But if the skb fragment pages are
> originating from a page_pool, calling put_page on them will trigger a
> page_pool leak which will eventually result in a crash.
> 
> This leak can be easily observed when using CONFIG_DEBUG_VM and doing
> ipsec + gre (non offloaded) forwarding:
> 
>   BUG: Bad page state in process ksoftirqd/16  pfn:1451b6
>   page:00000000de2b8d32 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1451b6000 pfn:0x1451b6
>   flags: 0x200000000000000(node=0|zone=2)
>   page_type: 0xffffffff()
>   raw: 0200000000000000 dead000000000040 ffff88810d23c000 0000000000000000
>   raw: 00000001451b6000 0000000000000001 00000000ffffffff 0000000000000000
>   page dumped because: page_pool leak
>   Modules linked in: ip_gre gre mlx5_ib mlx5_core xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink iptable_nat nf_nat xt_addrtype br_netfilter rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_iscsi ib_umad rdma_cm ib_ipoib iw_cm ib_cm ib_uverbs ib_core overlay zram zsmalloc fuse [last unloaded: mlx5_core]
>   CPU: 16 PID: 96 Comm: ksoftirqd/16 Not tainted 6.8.0-rc4+ #22
>   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
>   Call Trace:
>    <TASK>
>    dump_stack_lvl+0x36/0x50
>    bad_page+0x70/0xf0
>    free_unref_page_prepare+0x27a/0x460
>    free_unref_page+0x38/0x120
>    esp_ssg_unref.isra.0+0x15f/0x200
>    esp_output_tail+0x66d/0x780
>    esp_xmit+0x2c5/0x360
>    validate_xmit_xfrm+0x313/0x370
>    ? validate_xmit_skb+0x1d/0x330
>    validate_xmit_skb_list+0x4c/0x70
>    sch_direct_xmit+0x23e/0x350
>    __dev_queue_xmit+0x337/0xba0
>    ? nf_hook_slow+0x3f/0xd0
>    ip_finish_output2+0x25e/0x580
>    iptunnel_xmit+0x19b/0x240
>    ip_tunnel_xmit+0x5fb/0xb60
>    ipgre_xmit+0x14d/0x280 [ip_gre]
>    dev_hard_start_xmit+0xc3/0x1c0
>    __dev_queue_xmit+0x208/0xba0
>    ? nf_hook_slow+0x3f/0xd0
>    ip_finish_output2+0x1ca/0x580
>    ip_sublist_rcv_finish+0x32/0x40
>    ip_sublist_rcv+0x1b2/0x1f0
>    ? ip_rcv_finish_core.constprop.0+0x460/0x460
>    ip_list_rcv+0x103/0x130
>    __netif_receive_skb_list_core+0x181/0x1e0
>    netif_receive_skb_list_internal+0x1b3/0x2c0
>    napi_gro_receive+0xc8/0x200
>    gro_cell_poll+0x52/0x90
>    __napi_poll+0x25/0x1a0
>    net_rx_action+0x28e/0x300
>    __do_softirq+0xc3/0x276
>    ? sort_range+0x20/0x20
>    run_ksoftirqd+0x1e/0x30
>    smpboot_thread_fn+0xa6/0x130
>    kthread+0xcd/0x100
>    ? kthread_complete_and_exit+0x20/0x20
>    ret_from_fork+0x31/0x50
>    ? kthread_complete_and_exit+0x20/0x20
>    ret_from_fork_asm+0x11/0x20
>    </TASK>
> 
> The suggested fix is to use a new wrapper that covers page refcounting
> for page_pool pages as well.
> 
> Signed-off-by: Dragos Tatulea <dtatulea@...dia.com>
> Reported-by: Anatoli N.Chechelnickiy <Anatoli.Chechelnickiy@...nterpipe.biz>
> Reported-by: Ian Kumlien <ian.kumlien@...il.com>
> ---
> 
> Changes in v2:
> - Added napi_page_unref api based on discussion in v1 [0].
> 
> [0]https://lore.kernel.org/netdev/CAHS8izOoO-EovwMwAm9tLYetwikNPxC0FKyVGu1TPJWSz4bGoA@mail.gmail.com/T/#t
> 
Jakub, are you sure that it is ok to have all this in a single patch?

Thanks,
Dragos

> ---
>  include/linux/skbuff.h | 10 +++++++---
>  net/ipv4/esp4.c        | 16 ++++++++++------
>  net/ipv6/esp6.c        | 16 ++++++++++------
>  3 files changed, 27 insertions(+), 15 deletions(-)
> 
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 696e7680656f..009603db2a43 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -3453,10 +3453,8 @@ int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
>  bool napi_pp_put_page(struct page *page, bool napi_safe);
>  
>  static inline void
> -napi_frag_unref(skb_frag_t *frag, bool recycle, bool napi_safe)
> +napi_page_unref(struct page *page, bool recycle, bool napi_safe)
>  {
> -	struct page *page = skb_frag_page(frag);
> -
>  #ifdef CONFIG_PAGE_POOL
>  	if (recycle && napi_pp_put_page(page, napi_safe))
>  		return;
> @@ -3464,6 +3462,12 @@ napi_frag_unref(skb_frag_t *frag, bool recycle, bool napi_safe)
>  	put_page(page);
>  }
>  
> +static inline void
> +napi_frag_unref(skb_frag_t *frag, bool recycle, bool napi_safe)
> +{
> +	napi_page_unref(skb_frag_page(frag), recycle, napi_safe);
> +}
> +
>  /**
>   * __skb_frag_unref - release a reference on a paged fragment.
>   * @frag: the paged fragment
> diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
> index 4dd9e5040672..3126aeb0588d 100644
> --- a/net/ipv4/esp4.c
> +++ b/net/ipv4/esp4.c
> @@ -95,7 +95,7 @@ static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
>  			     __alignof__(struct scatterlist));
>  }
>  
> -static void esp_ssg_unref(struct xfrm_state *x, void *tmp)
> +static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb)
>  {
>  	struct crypto_aead *aead = x->data;
>  	int extralen = 0;
> @@ -112,9 +112,13 @@ static void esp_ssg_unref(struct xfrm_state *x, void *tmp)
>  	/* Unref skb_frag_pages in the src scatterlist if necessary.
>  	 * Skip the first sg which comes from skb->data.
>  	 */
> -	if (req->src != req->dst)
> -		for (sg = sg_next(req->src); sg; sg = sg_next(sg))
> -			put_page(sg_page(sg));
> +	if (req->src != req->dst) {
> +		for (sg = sg_next(req->src); sg; sg = sg_next(sg)) {
> +			struct page *page = sg_page(sg);
> +
> +			napi_page_unref(page, skb->pp_recycle, false);
> +		}
> +	}
>  }
>  
>  #ifdef CONFIG_INET_ESPINTCP
> @@ -260,7 +264,7 @@ static void esp_output_done(void *data, int err)
>  	}
>  
>  	tmp = ESP_SKB_CB(skb)->tmp;
> -	esp_ssg_unref(x, tmp);
> +	esp_ssg_unref(x, tmp, skb);
>  	kfree(tmp);
>  
>  	if (xo && (xo->flags & XFRM_DEV_RESUME)) {
> @@ -639,7 +643,7 @@ int esp_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *
>  	}
>  
>  	if (sg != dsg)
> -		esp_ssg_unref(x, tmp);
> +		esp_ssg_unref(x, tmp, skb);
>  
>  	if (!err && x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
>  		err = esp_output_tail_tcp(x, skb);
> diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c
> index 6e6efe026cdc..7bbe19e74cf0 100644
> --- a/net/ipv6/esp6.c
> +++ b/net/ipv6/esp6.c
> @@ -112,7 +112,7 @@ static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
>  			     __alignof__(struct scatterlist));
>  }
>  
> -static void esp_ssg_unref(struct xfrm_state *x, void *tmp)
> +static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb)
>  {
>  	struct crypto_aead *aead = x->data;
>  	int extralen = 0;
> @@ -129,9 +129,13 @@ static void esp_ssg_unref(struct xfrm_state *x, void *tmp)
>  	/* Unref skb_frag_pages in the src scatterlist if necessary.
>  	 * Skip the first sg which comes from skb->data.
>  	 */
> -	if (req->src != req->dst)
> -		for (sg = sg_next(req->src); sg; sg = sg_next(sg))
> -			put_page(sg_page(sg));
> +	if (req->src != req->dst) {
> +		for (sg = sg_next(req->src); sg; sg = sg_next(sg)) {
> +			struct page *page = sg_page(sg);
> +
> +			napi_page_unref(page, skb->pp_recycle, false);
> +		}
> +	}
>  }
>  
>  #ifdef CONFIG_INET6_ESPINTCP
> @@ -294,7 +298,7 @@ static void esp_output_done(void *data, int err)
>  	}
>  
>  	tmp = ESP_SKB_CB(skb)->tmp;
> -	esp_ssg_unref(x, tmp);
> +	esp_ssg_unref(x, tmp, skb);
>  	kfree(tmp);
>  
>  	esp_output_encap_csum(skb);
> @@ -677,7 +681,7 @@ int esp6_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info
>  	}
>  
>  	if (sg != dsg)
> -		esp_ssg_unref(x, tmp);
> +		esp_ssg_unref(x, tmp, skb);
>  
>  	if (!err && x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
>  		err = esp_output_tail_tcp(x, skb);

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