linux-kernel - [PATCH v3] net: linearizing skb when downgrade gso

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20240717053540.2438-1-dracodingfly@gmail.com>
Date: Wed, 17 Jul 2024 13:35:40 +0800
From: Fred Li <dracodingfly@...il.com>
To: pabeni@...hat.com,
	willemdebruijn.kernel@...il.com,
	herbert@...dor.apana.org.au
Cc: bpf@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org,
	song@...nel.org,
	yonghong.song@...ux.dev,
	john.fastabend@...il.com,
	kpsingh@...nel.org,
	Fred Li <dracodingfly@...il.com>
Subject: [PATCH v3] net: linearizing skb when downgrade gso_size

Linearizing skb when downgrade gso_size because it may
trigger the BUG_ON when segment skb as described in [1].

v3 changes:
  linearize skb if having frag_list as Willem de Bruijn suggested[2].

[1] https://lore.kernel.org/all/20240626065555.35460-2-dracodingfly@gmail.com/
[2] https://lore.kernel.org/all/668d5cf1ec330_1c18c32947@willemb.c.googlers.com.notmuch/

Signed-off-by: Fred Li <dracodingfly@...il.com>
---
 net/core/filter.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index df4578219e82..70919b532d68 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3525,13 +3525,21 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
 	if (skb_is_gso(skb)) {
 		struct skb_shared_info *shinfo = skb_shinfo(skb);
 
-		/* Due to header grow, MSS needs to be downgraded. */
-		if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
-			skb_decrease_gso_size(shinfo, len_diff);
-
 		/* Header must be checked, and gso_segs recomputed. */
 		shinfo->gso_type |= gso_type;
 		shinfo->gso_segs = 0;
+
+		/* Due to header grow, MSS needs to be downgraded.
+		 * There is BUG_ON When segment the frag_list with
+		 * head_frag true so linearize skb after downgrade
+		 * the MSS.
+		 */
+		if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) {
+			skb_decrease_gso_size(shinfo, len_diff);
+			if (shinfo->frag_list)
+				return skb_linearize(skb);
+		}
+
 	}
 
 	return 0;
-- 
2.33.0