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kernel: fix crash with multicast-to-unicast and fraglist GRO 

Avoid calls to skb_copy, which creates invalid packets that cause a crash
on segmentation

Signed-off-by: Felix Fietkau <nbd@nbd.name>
This commit is contained in:
Felix Fietkau 2024-04-27 20:32:59 +02:00
parent fe9d2ccbc3
commit 45a8e962a5
4 changed files with 164 additions and 0 deletions
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23
target/linux/generic/pending-6.1/681-net-bridge-fix-multicast-to-unicast-with-fraglist-GS.patch Normal file
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@ -0,0 +1,23 @@
From: Felix Fietkau <nbd@nbd.name>
Date: Sat, 27 Apr 2024 18:54:25 +0200
Subject: [PATCH] net: bridge: fix multicast-to-unicast with fraglist GSO
Calling skb_copy on a SKB_GSO_FRAGLIST skb is not valid, since it returns
an invalid linearized skb. This code only needs to change the ethernet
header, so pskb_copy is the right function to call here.
Fixes: 6db6f0eae605 ("bridge: multicast to unicast")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -261,7 +261,7 @@ static void maybe_deliver_addr(struct ne
if (skb->dev == p->dev && ether_addr_equal(src, addr))
return;
- skb = skb_copy(skb, GFP_ATOMIC);
+ skb = pskb_copy(skb, GFP_ATOMIC);
if (!skb) {
DEV_STATS_INC(dev, tx_dropped);
return;

59
target/linux/generic/pending-6.1/682-net-core-reject-skb_copy-_expand-for-fraglist-GSO-sk.patch Normal file
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@ -0,0 +1,59 @@
From: Felix Fietkau <nbd@nbd.name>
Date: Sat, 27 Apr 2024 19:29:45 +0200
Subject: [PATCH] net: core: reject skb_copy(_expand) for fraglist GSO skbs
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>
---
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1720,11 +1720,17 @@ static inline int skb_alloc_rx_flag(cons
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;
@@ -2037,12 +2043,17 @@ struct sk_buff *skb_copy_expand(const st
/*
* 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;

23
target/linux/generic/pending-6.6/681-net-bridge-fix-multicast-to-unicast-with-fraglist-GS.patch Normal file
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@ -0,0 +1,23 @@
From: Felix Fietkau <nbd@nbd.name>
Date: Sat, 27 Apr 2024 18:54:25 +0200
Subject: [PATCH] net: bridge: fix multicast-to-unicast with fraglist GSO
Calling skb_copy on a SKB_GSO_FRAGLIST skb is not valid, since it returns
an invalid linearized skb. This code only needs to change the ethernet
header, so pskb_copy is the right function to call here.
Fixes: 6db6f0eae605 ("bridge: multicast to unicast")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -266,7 +266,7 @@ static void maybe_deliver_addr(struct ne
if (skb->dev == p->dev && ether_addr_equal(src, addr))
return;
- skb = skb_copy(skb, GFP_ATOMIC);
+ skb = pskb_copy(skb, GFP_ATOMIC);
if (!skb) {
DEV_STATS_INC(dev, tx_dropped);
return;

59
target/linux/generic/pending-6.6/682-net-core-reject-skb_copy-_expand-for-fraglist-GSO-sk.patch Normal file
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@ -0,0 +1,59 @@
From: Felix Fietkau <nbd@nbd.name>
Date: Sat, 27 Apr 2024 19:29:45 +0200
Subject: [PATCH] net: core: reject skb_copy(_expand) for fraglist GSO skbs
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>
---
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1971,11 +1971,17 @@ static inline int skb_alloc_rx_flag(cons
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;
@@ -2303,12 +2309,17 @@ struct sk_buff *skb_copy_expand(const st
/*
* 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;