[PATCH 6.1] net: fix crash when config small gso_max_size/gso_ipv4_max_size

[PATCH 6.1] net: fix crash when config small gso_max_size/gso_ipv4_max_size

[Bin Lan]

From: Wang Liang <wangliang74@huawei.com>

[ Upstream commit 9ab5cf19fb0e4680f95e506d6c544259bf1111c4 ]

Config a small gso_max_size/gso_ipv4_max_size will lead to an underflow
in sk_dst_gso_max_size(), which may trigger a BUG_ON crash,
because sk->sk_gso_max_size would be much bigger than device limits.
Call Trace:
tcp_write_xmit
    tso_segs = tcp_init_tso_segs(skb, mss_now);
        tcp_set_skb_tso_segs
            tcp_skb_pcount_set
                // skb->len = 524288, mss_now = 8
                // u16 tso_segs = 524288/8 = 65535 -> 0
                tso_segs = DIV_ROUND_UP(skb->len, mss_now)
    BUG_ON(!tso_segs)
Add check for the minimum value of gso_max_size and gso_ipv4_max_size.

Fixes: 46e6b992c250 ("rtnetlink: allow GSO maximums to be set on device creation")
Fixes: 9eefedd58ae1 ("net: add gso_ipv4_max_size and gro_ipv4_max_size per device")
Signed-off-by: Wang Liang <wangliang74@huawei.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241023035213.517386-1-wangliang74@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Resolve minor conflicts to fix CVE-2024-50258 ]
Signed-off-by: Bin Lan <bin.lan.cn@windriver.com>
---
 net/core/rtnetlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index afb52254a47e..45c54fb9ad03 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1939,7 +1939,7 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
 	[IFLA_NUM_TX_QUEUES]	= { .type = NLA_U32 },
 	[IFLA_NUM_RX_QUEUES]	= { .type = NLA_U32 },
 	[IFLA_GSO_MAX_SEGS]	= { .type = NLA_U32 },
-	[IFLA_GSO_MAX_SIZE]	= { .type = NLA_U32 },
+	[IFLA_GSO_MAX_SIZE]	= NLA_POLICY_MIN(NLA_U32, MAX_TCP_HEADER + 1),
 	[IFLA_PHYS_PORT_ID]	= { .type = NLA_BINARY, .len = MAX_PHYS_ITEM_ID_LEN },
 	[IFLA_CARRIER_CHANGES]	= { .type = NLA_U32 },  /* ignored */
 	[IFLA_PHYS_SWITCH_ID]	= { .type = NLA_BINARY, .len = MAX_PHYS_ITEM_ID_LEN },
-- 
2.43.0

Re: [PATCH 6.1] net: fix crash when config small gso_max_size/gso_ipv4_max_size

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

The upstream commit SHA1 provided is correct: 9ab5cf19fb0e4680f95e506d6c544259bf1111c4

WARNING: Author mismatch between patch and upstream commit:
Backport author: Bin Lan <bin.lan.cn@windriver.com>
Commit author: Wang Liang <wangliang74@huawei.com>


Status in newer kernel trees:
6.12.y | Present (exact SHA1)
6.11.y | Present (different SHA1: e72fd1389a53)
6.6.y | Present (different SHA1: ac5977001eee)
6.1.y | Not found

Note: The patch differs from the upstream commit:
---
--- -	2024-11-22 08:40:39.766289882 -0500
+++ /tmp/tmp.58u8agz5Rn	2024-11-22 08:40:39.760746269 -0500
@@ -1,3 +1,5 @@
+[ Upstream commit 9ab5cf19fb0e4680f95e506d6c544259bf1111c4 ]
+
 Config a small gso_max_size/gso_ipv4_max_size will lead to an underflow
 in sk_dst_gso_max_size(), which may trigger a BUG_ON crash,
 because sk->sk_gso_max_size would be much bigger than device limits.
@@ -18,15 +20,17 @@
 Reviewed-by: Eric Dumazet <edumazet@google.com>
 Link: https://patch.msgid.link/20241023035213.517386-1-wangliang74@huawei.com
 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+[ Resolve minor conflicts to fix CVE-2024-50258 ]
+Signed-off-by: Bin Lan <bin.lan.cn@windriver.com>
 ---
- net/core/rtnetlink.c | 4 ++--
- 1 file changed, 2 insertions(+), 2 deletions(-)
+ net/core/rtnetlink.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
 
 diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
-index e30e7ea0207d0..2ba5cd965d3fa 100644
+index afb52254a47e..45c54fb9ad03 100644
 --- a/net/core/rtnetlink.c
 +++ b/net/core/rtnetlink.c
-@@ -2032,7 +2032,7 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
+@@ -1939,7 +1939,7 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
  	[IFLA_NUM_TX_QUEUES]	= { .type = NLA_U32 },
  	[IFLA_NUM_RX_QUEUES]	= { .type = NLA_U32 },
  	[IFLA_GSO_MAX_SEGS]	= { .type = NLA_U32 },
@@ -35,12 +39,6 @@
  	[IFLA_PHYS_PORT_ID]	= { .type = NLA_BINARY, .len = MAX_PHYS_ITEM_ID_LEN },
  	[IFLA_CARRIER_CHANGES]	= { .type = NLA_U32 },  /* ignored */
  	[IFLA_PHYS_SWITCH_ID]	= { .type = NLA_BINARY, .len = MAX_PHYS_ITEM_ID_LEN },
-@@ -2057,7 +2057,7 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
- 	[IFLA_TSO_MAX_SIZE]	= { .type = NLA_REJECT },
- 	[IFLA_TSO_MAX_SEGS]	= { .type = NLA_REJECT },
- 	[IFLA_ALLMULTI]		= { .type = NLA_REJECT },
--	[IFLA_GSO_IPV4_MAX_SIZE]	= { .type = NLA_U32 },
-+	[IFLA_GSO_IPV4_MAX_SIZE]	= NLA_POLICY_MIN(NLA_U32, MAX_TCP_HEADER + 1),
- 	[IFLA_GRO_IPV4_MAX_SIZE]	= { .type = NLA_U32 },
- };
- 
+-- 
+2.43.0
+
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.1.y        |  Success    |  Success   |