From: HanQuan Date: Thu, 4 Jun 2026 14:46:25 +0000 (+0000) Subject: net: add pskb_may_pull() to skb_gro_receive_list() X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=f2bb3434544454099a5b6dec213567267b05d79d;p=thirdparty%2Fkernel%2Flinux.git net: add pskb_may_pull() to skb_gro_receive_list() skb_gro_receive_list() calls skb_pull(skb, skb_gro_offset(skb)) without first ensuring the data is in the linear area via pskb_may_pull(). When the skb arrives via napi_gro_frags(), skb_headlen can be 0 (all data in page fragments) while skb_gro_offset is non-zero (after IP+TCP header parsing). The skb_pull() then decrements skb->len by skb_gro_offset but skb->data_len stays unchanged, hitting BUG_ON(skb->len < skb->data_len) in __skb_pull(). The UDP fraglist GRO path already contains this guard at udp_offload.c:749. Adding it to skb_gro_receive_list() itself provides centralized protection for all callers (TCP, UDP, and any future protocols), and ensures the precondition of skb_pull() is satisfied before it is called. On pskb_may_pull() failure, set NAPI_GRO_CB(skb)->flush = 1 so the skb is not held as a new GRO head and is instead delivered through the normal receive path, matching the UDP handling. Fixes: 8d95dc474f85 ("net: add code for TCP fraglist GRO") Reported-by: HanQuan Reported-by: MingXuan Signed-off-by: HanQuan Reviewed-by: Eric Dumazet Signed-off-by: Jakub Kicinski --- diff --git a/net/core/gro.c b/net/core/gro.c index a84753983467..35f2f708f010 100644 --- a/net/core/gro.c +++ b/net/core/gro.c @@ -232,6 +232,11 @@ int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb) if (unlikely(p->len + skb->len >= 65536)) return -E2BIG; + if (!pskb_may_pull(skb, skb_gro_offset(skb))) { + NAPI_GRO_CB(skb)->flush = 1; + return -ENOMEM; + } + if (NAPI_GRO_CB(p)->last == p) skb_shinfo(p)->frag_list = skb; else