CVE-2025-21629: net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets
Description
In the Linux kernel, the following vulnerability has been resolved:
net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets
The blamed commit disabled hardware offoad of IPv6 packets with
extension headers on devices that advertise NETIF_F_IPV6_CSUM,
based on the definition of that feature in skbuff.h:
* * - %NETIF_F_IPV6_CSUM
* - Driver (device) is only able to checksum plain
* TCP or UDP packets over IPv6. These are specifically
* unencapsulated packets of the form IPv6|TCP or
* IPv6|UDP where the Next Header field in the IPv6
* header is either TCP or UDP. IPv6 extension headers
* are not supported with this feature. This feature
* cannot be set in features for a device with
* NETIF_F_HW_CSUM also set. This feature is being
* DEPRECATED (see below).
The change causes skb_warn_bad_offload to fire for BIG TCP
packets.
[ 496.310233] WARNING: CPU: 13 PID: 23472 at net/core/dev.c:3129 skb_warn_bad_offload+0xc4/0xe0
[ 496.310297] ? skb_warn_bad_offload+0xc4/0xe0
[ 496.310300] skb_checksum_help+0x129/0x1f0
[ 496.310303] skb_csum_hwoffload_help+0x150/0x1b0
[ 496.310306] validate_xmit_skb+0x159/0x270
[ 496.310309] validate_xmit_skb_list+0x41/0x70
[ 496.310312] sch_direct_xmit+0x5c/0x250
[ 496.310317] __qdisc_run+0x388/0x620
BIG TCP introduced an IPV6_TLV_JUMBO IPv6 extension header to
communicate packet length, as this is an IPv6 jumbogram. But, the
feature is only enabled on devices that s...
Classification
CVE ID: CVE-2025-21629
Affected Products
Vendor: Linux
Product: Linux
Exploit Prediction Scoring System (EPSS)
EPSS Score: 0.05% (probability of being exploited)
EPSS Percentile: 17.81% (scored less or equal to compared to others)
EPSS Date: 2025-02-13 (when was this score calculated)
References
https://git.kernel.org/stable/c/ac9cfef69565021c9e1022a493a9c40b03e2caf9https://git.kernel.org/stable/c/95ccf006bbc8b59044313b8c309dcf29c546abd4
https://git.kernel.org/stable/c/d3b7a9c7597b779039a51d7b34116fbe424bf2b7
https://git.kernel.org/stable/c/68e068cabd2c6c533ef934c2e5151609cf6ecc6d