[PATCH 6.8 075/336] net: core: reject skb_copy(_expand) for fraglist GSO skbs

Greg Kroah-Hartman
2024-05-14T10:30:44Z

From: Felix Fietkau <nbd@nbd.name>

[ Upstream commit d091e579b864fa790dd6a0cd537a22c383126681 ]

SKB_GSO_FRAGLIST skbs must not be linearized, otherwise they become
invalid. Return NULL if such an skb is passed to skb_copy or
skb_copy_expand, in order to prevent a crash on a potential later
call to skb_gso_segment.

Fixes: 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/skbuff.c | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 71dee435d549d..570269c477549 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2014,11 +2014,17 @@ static inline int skb_alloc_rx_flag(const struct sk_buff *skb)

struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
{
- int headerlen = skb_headroom(skb);
- unsigned int size = skb_end_offset(skb) + skb->data_len;
- struct sk_buff *n = __alloc_skb(size, gfp_mask,
- skb_alloc_rx_flag(skb), NUMA_NO_NODE);
+ struct sk_buff *n;
+ unsigned int size;
+ int headerlen;
+
+ if (WARN_ON_ONCE(skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST))
+ return NULL;

+ headerlen = skb_headroom(skb);
+ size = skb_end_offset(skb) + skb->data_len;
+ n = __alloc_skb(size, gfp_mask,
+ skb_alloc_rx_flag(skb), NUMA_NO_NODE);
if (!n)
return NULL;

@@ -2346,12 +2352,17 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
/*
* Allocate the copy buffer
*/
- struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
- gfp_mask, skb_alloc_rx_flag(skb),
- NUMA_NO_NODE);
- int oldheadroom = skb_headroom(skb);
int head_copy_len, head_copy_off;
+ struct sk_buff *n;
+ int oldheadroom;
+
+ if (WARN_ON_ONCE(skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST))
+ return NULL;

+ oldheadroom = skb_headroom(skb);
+ n = __alloc_skb(newheadroom + skb->len + newtailroom,
+ gfp_mask, skb_alloc_rx_flag(skb),
+ NUMA_NO_NODE);
if (!n)
return NULL;

--
2.43.0