From: Dongseok Yi <dseok.yi@samsung.com>
To: "David S. Miller" <davem@davemloft.net>,
Willem de Bruijn <willemb@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>,
Miaohe Lin <linmiaohe@huawei.com>,
Paolo Abeni <pabeni@redhat.com>, Florian Westphal <fw@strlen.de>,
Al Viro <viro@zeniv.linux.org.uk>,
Guillaume Nault <gnault@redhat.com>,
Yunsheng Lin <linyunsheng@huawei.com>,
Steffen Klassert <steffen.klassert@secunet.com>,
Yadu Kishore <kyk.segfault@gmail.com>,
Marco Elver <elver@google.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
namkyu78.kim@samsung.com, Dongseok Yi <dseok.yi@samsung.com>
Subject: [PATCH net v2] net: fix use-after-free when UDP GRO with shared fraglist
Date: Thu, 7 Jan 2021 09:39:13 +0900 [thread overview]
Message-ID: <1609979953-181868-1-git-send-email-dseok.yi@samsung.com> (raw)
In-Reply-To: <1609750005-115609-1-git-send-email-dseok.yi@samsung.com>
skbs in fraglist could be shared by a BPF filter loaded at TC. It
triggers skb_ensure_writable -> pskb_expand_head ->
skb_clone_fraglist -> skb_get on each skb in the fraglist.
While tcpdump, sk_receive_queue of PF_PACKET has the original fraglist.
But the same fraglist is queued to PF_INET (or PF_INET6) as the fraglist
chain made by skb_segment_list.
If the new skb (not fraglist) is queued to one of the sk_receive_queue,
multiple ptypes can see this. The skb could be released by ptypes and
it causes use-after-free.
[ 4443.426215] ------------[ cut here ]------------
[ 4443.426222] refcount_t: underflow; use-after-free.
[ 4443.426291] WARNING: CPU: 7 PID: 28161 at lib/refcount.c:190
refcount_dec_and_test_checked+0xa4/0xc8
[ 4443.426726] pstate: 60400005 (nZCv daif +PAN -UAO)
[ 4443.426732] pc : refcount_dec_and_test_checked+0xa4/0xc8
[ 4443.426737] lr : refcount_dec_and_test_checked+0xa0/0xc8
[ 4443.426808] Call trace:
[ 4443.426813] refcount_dec_and_test_checked+0xa4/0xc8
[ 4443.426823] skb_release_data+0x144/0x264
[ 4443.426828] kfree_skb+0x58/0xc4
[ 4443.426832] skb_queue_purge+0x64/0x9c
[ 4443.426844] packet_set_ring+0x5f0/0x820
[ 4443.426849] packet_setsockopt+0x5a4/0xcd0
[ 4443.426853] __sys_setsockopt+0x188/0x278
[ 4443.426858] __arm64_sys_setsockopt+0x28/0x38
[ 4443.426869] el0_svc_common+0xf0/0x1d0
[ 4443.426873] el0_svc_handler+0x74/0x98
[ 4443.426880] el0_svc+0x8/0xc
Fixes: 3a1296a38d0c (net: Support GRO/GSO fraglist chaining.)
Signed-off-by: Dongseok Yi <dseok.yi@samsung.com>
Acked-by: Willem de Bruijn <willemb@google.com>
---
net/core/skbuff.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
v2: Expand the commit message to clarify a BPF filter loaded
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f62cae3..1dcbda8 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3655,7 +3655,8 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb,
unsigned int delta_truesize = 0;
unsigned int delta_len = 0;
struct sk_buff *tail = NULL;
- struct sk_buff *nskb;
+ struct sk_buff *nskb, *tmp;
+ int err;
skb_push(skb, -skb_network_offset(skb) + offset);
@@ -3665,11 +3666,28 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb,
nskb = list_skb;
list_skb = list_skb->next;
+ err = 0;
+ if (skb_shared(nskb)) {
+ tmp = skb_clone(nskb, GFP_ATOMIC);
+ if (tmp) {
+ kfree_skb(nskb);
+ nskb = tmp;
+ err = skb_unclone(nskb, GFP_ATOMIC);
+ } else {
+ err = -ENOMEM;
+ }
+ }
+
if (!tail)
skb->next = nskb;
else
tail->next = nskb;
+ if (unlikely(err)) {
+ nskb->next = list_skb;
+ goto err_linearize;
+ }
+
tail = nskb;
delta_len += nskb->len;
--
2.7.4
next prev parent reply other threads:[~2021-01-07 0:51 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20210104085750epcas2p1a5b22559d87df61ef3c8215ae0b470b5@epcas2p1.samsung.com>
2021-01-04 8:46 ` [PATCH net] net: fix use-after-free when UDP GRO with shared fraglist Dongseok Yi
2021-01-04 21:03 ` Willem de Bruijn
2021-01-06 1:29 ` Dongseok Yi
2021-01-06 3:07 ` Willem de Bruijn
2021-01-06 3:32 ` Dongseok Yi
2021-01-06 17:13 ` Willem de Bruijn
2021-04-17 3:44 ` Yunsheng Lin
2021-04-19 0:35 ` Dongseok Yi
2021-04-21 9:42 ` Yunsheng Lin
2021-04-21 11:04 ` Dongseok Yi
[not found] ` <CGME20210107005028epcas2p35dfa745fd92e31400024874f54243556@epcas2p3.samsung.com>
2021-01-07 0:39 ` Dongseok Yi [this message]
2021-01-07 11:05 ` [PATCH net v2] " Daniel Borkmann
2021-01-07 11:40 ` Dongseok Yi
2021-01-07 12:49 ` Daniel Borkmann
2021-01-07 13:05 ` Willem de Bruijn
2021-01-07 13:33 ` Daniel Borkmann
2021-01-07 14:44 ` Willem de Bruijn
2021-01-08 10:32 ` Daniel Borkmann
[not found] ` <CGME20210108024017epcas2p455fe96b8483880f9b7a654dbcf600b20@epcas2p4.samsung.com>
2021-01-08 2:28 ` [PATCH net v3] " Dongseok Yi
2021-01-08 10:18 ` Daniel Borkmann
2021-01-09 3:14 ` Jakub Kicinski
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