From 00b229f762b020eebf55a52b984aec76ae0ad966 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Tue, 19 Jan 2021 17:56:56 +0100 Subject: [PATCH] net: fix GSO for SG-enabled devices The commit dbd50f238dec ("net: move the hsize check to the else block in skb_segment") introduced a data corruption for devices supporting scatter-gather. The problem boils down to signed/unsigned comparison given unexpected results: if signed 'hsize' is negative, it will be considered greater than a positive 'len', which is unsigned. This commit addresses resorting to the old checks order, so that 'hsize' never has a negative value when compared with 'len'. v1 -> v2: - reorder hsize checks instead of explicit cast (Alex) Bisected-by: Matthieu Baerts Fixes: dbd50f238dec ("net: move the hsize check to the else block in skb_segment") Signed-off-by: Paolo Abeni Reviewed-by: Xin Long Link: https://lore.kernel.org/r/861947c2d2d087db82af93c21920ce8147d15490.1611074818.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski --- net/core/skbuff.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index e835193cabcc..cf2c4dcf4257 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3938,10 +3938,10 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, skb_release_head_state(nskb); __skb_push(nskb, doffset); } else { + if (hsize < 0) + hsize = 0; if (hsize > len || !sg) hsize = len; - else if (hsize < 0) - hsize = 0; nskb = __alloc_skb(hsize + doffset + headroom, GFP_ATOMIC, skb_alloc_rx_flag(head_skb), -- GitLab