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authorSubash Abhinov Kasiviswanathan <quic_subashab@quicinc.com>2022-12-14 23:11:58 -0700
committerJakub Kicinski <kuba@kernel.org>2022-12-16 21:18:58 -0800
commit2d7afdcbc9d32423f177ee12b7c93783aea338fb (patch)
treeef275c6ef0a7c083be4a0e70bcb4a38feb107a57 /net
parent214964a13ab56a9757d146b79b468a7ca190fbfb (diff)
downloadlwn-2d7afdcbc9d32423f177ee12b7c93783aea338fb.tar.gz
lwn-2d7afdcbc9d32423f177ee12b7c93783aea338fb.zip
skbuff: Account for tail adjustment during pull operations
Extending the tail can have some unexpected side effects if a program uses a helper like BPF_FUNC_skb_pull_data to read partial content beyond the head skb headlen when all the skbs in the gso frag_list are linear with no head_frag - kernel BUG at net/core/skbuff.c:4219! pc : skb_segment+0xcf4/0xd2c lr : skb_segment+0x63c/0xd2c Call trace: skb_segment+0xcf4/0xd2c __udp_gso_segment+0xa4/0x544 udp4_ufo_fragment+0x184/0x1c0 inet_gso_segment+0x16c/0x3a4 skb_mac_gso_segment+0xd4/0x1b0 __skb_gso_segment+0xcc/0x12c udp_rcv_segment+0x54/0x16c udp_queue_rcv_skb+0x78/0x144 udp_unicast_rcv_skb+0x8c/0xa4 __udp4_lib_rcv+0x490/0x68c udp_rcv+0x20/0x30 ip_protocol_deliver_rcu+0x1b0/0x33c ip_local_deliver+0xd8/0x1f0 ip_rcv+0x98/0x1a4 deliver_ptype_list_skb+0x98/0x1ec __netif_receive_skb_core+0x978/0xc60 Fix this by marking these skbs as GSO_DODGY so segmentation can handle the tail updates accordingly. Fixes: 3dcbdb134f32 ("net: gso: Fix skb_segment splat when splitting gso_size mangled skb having linear-headed frag_list") Signed-off-by: Sean Tranchetti <quic_stranche@quicinc.com> Signed-off-by: Subash Abhinov Kasiviswanathan <quic_subashab@quicinc.com> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com> Link: https://lore.kernel.org/r/1671084718-24796-1-git-send-email-quic_subashab@quicinc.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
-rw-r--r--net/core/skbuff.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 3cbba7099c0f..4a0eb5593275 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2482,6 +2482,9 @@ void *__pskb_pull_tail(struct sk_buff *skb, int delta)
insp = list;
} else {
/* Eaten partially. */
+ if (skb_is_gso(skb) && !list->head_frag &&
+ skb_headlen(list))
+ skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
if (skb_shared(list)) {
/* Sucks! We need to fork list. :-( */