[PATCH net 3/4] virtio-net: create a helper to check received mergeable buffer's length
From: Bui Quang Minh <hidden>
Date: 2025-06-25 16:10:34
Also in:
bpf, lkml, virtualization
Subsystem:
networking drivers, the rest, virtio net driver · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, "Michael S. Tsirkin", Jason Wang
Currently, we have repeated code to check the received mergeable buffer's length with allocated size. This commit creates a helper to do that and converts current code to use it. Signed-off-by: Bui Quang Minh <redacted> --- drivers/net/virtio_net.c | 68 +++++++++++++++++----------------------- 1 file changed, 29 insertions(+), 39 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 6f9fedad4a5e..844cb2a78be0 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c@@ -778,6 +778,26 @@ static unsigned int mergeable_ctx_to_truesize(void *mrg_ctx) return (unsigned long)mrg_ctx & ((1 << MRG_CTX_HEADER_SHIFT) - 1); } +static int check_mergeable_len(struct net_device *dev, void *mrg_ctx, + unsigned int len) +{ + unsigned int headroom, tailroom, room, truesize; + + truesize = mergeable_ctx_to_truesize(mrg_ctx); + headroom = mergeable_ctx_to_headroom(mrg_ctx); + tailroom = headroom ? sizeof(struct skb_shared_info) : 0; + room = SKB_DATA_ALIGN(headroom + tailroom); + + if (len > truesize - room) { + pr_debug("%s: rx error: len %u exceeds truesize %lu\n", + dev->name, len, (unsigned long)(truesize - room)); + DEV_STATS_INC(dev, rx_length_errors); + return -1; + } + + return 0; +} + static struct sk_buff *virtnet_build_skb(void *buf, unsigned int buflen, unsigned int headroom, unsigned int len)
@@ -1819,8 +1839,7 @@ static struct page *xdp_linearize_page(struct net_device *dev, page_off += *len; while (--*num_buf) { - unsigned int headroom, tailroom, room; - unsigned int truesize, buflen; + unsigned int buflen; void *buf; void *ctx; int off;
@@ -1832,17 +1851,8 @@ static struct page *xdp_linearize_page(struct net_device *dev, p = virt_to_head_page(buf); off = buf - page_address(p); - truesize = mergeable_ctx_to_truesize(ctx); - headroom = mergeable_ctx_to_headroom(ctx); - tailroom = headroom ? sizeof(struct skb_shared_info) : 0; - room = SKB_DATA_ALIGN(headroom + tailroom); - - if (unlikely(buflen > truesize - room)) { + if (check_mergeable_len(dev, ctx, buflen)) { put_page(p); - pr_debug("%s: rx error: len %u exceeds truesize %lu\n", - dev->name, buflen, - (unsigned long)(truesize - room)); - DEV_STATS_INC(dev, rx_length_errors); goto err_buf; }
@@ -2143,7 +2153,6 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev, struct virtnet_rq_stats *stats) { struct virtio_net_hdr_mrg_rxbuf *hdr = buf; - unsigned int headroom, tailroom, room; struct skb_shared_info *shinfo; unsigned int xdp_frags_truesz = 0; unsigned int truesize;
@@ -2189,20 +2198,14 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev, page = virt_to_head_page(buf); offset = buf - page_address(page); - truesize = mergeable_ctx_to_truesize(ctx); - headroom = mergeable_ctx_to_headroom(ctx); - tailroom = headroom ? sizeof(struct skb_shared_info) : 0; - room = SKB_DATA_ALIGN(headroom + tailroom); - - xdp_frags_truesz += truesize; - if (unlikely(len > truesize - room)) { + if (check_mergeable_len(dev, ctx, len)) { put_page(page); - pr_debug("%s: rx error: len %u exceeds truesize %lu\n", - dev->name, len, (unsigned long)(truesize - room)); - DEV_STATS_INC(dev, rx_length_errors); goto err; } + truesize = mergeable_ctx_to_truesize(ctx); + xdp_frags_truesz += truesize; + frag = &shinfo->frags[shinfo->nr_frags++]; skb_frag_fill_page_desc(frag, page, offset, len); if (page_is_pfmemalloc(page))
@@ -2416,18 +2419,12 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, struct sk_buff *head_skb, *curr_skb; unsigned int truesize = mergeable_ctx_to_truesize(ctx); unsigned int headroom = mergeable_ctx_to_headroom(ctx); - unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0; - unsigned int room = SKB_DATA_ALIGN(headroom + tailroom); head_skb = NULL; u64_stats_add(&stats->bytes, len - vi->hdr_len); - if (unlikely(len > truesize - room)) { - pr_debug("%s: rx error: len %u exceeds truesize %lu\n", - dev->name, len, (unsigned long)(truesize - room)); - DEV_STATS_INC(dev, rx_length_errors); + if (check_mergeable_len(dev, ctx, len)) goto err_skb; - } if (unlikely(vi->xdp_enabled)) { struct bpf_prog *xdp_prog;
@@ -2462,17 +2459,10 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, u64_stats_add(&stats->bytes, len); page = virt_to_head_page(buf); - truesize = mergeable_ctx_to_truesize(ctx); - headroom = mergeable_ctx_to_headroom(ctx); - tailroom = headroom ? sizeof(struct skb_shared_info) : 0; - room = SKB_DATA_ALIGN(headroom + tailroom); - if (unlikely(len > truesize - room)) { - pr_debug("%s: rx error: len %u exceeds truesize %lu\n", - dev->name, len, (unsigned long)(truesize - room)); - DEV_STATS_INC(dev, rx_length_errors); + if (check_mergeable_len(dev, ctx, len)) goto err_skb; - } + truesize = mergeable_ctx_to_truesize(ctx); curr_skb = virtnet_skb_append_frag(head_skb, curr_skb, page, buf, len, truesize); if (!curr_skb)
--
2.43.0