Description

In the Linux kernel, the following vulnerability has been resolved:

ip6_tunnel: make sure to pull inner header in __ip6_tnl_rcv()

syzbot found __ip6_tnl_rcv() could access unitiliazed data [1].

Call pskb_inet_may_pull() to fix this, and initialize ipv6h
variable after this call as it can change skb->head.

[1]
BUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]
BUG: KMSAN: uninit-value in INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]
BUG: KMSAN: uninit-value in IP6_ECN_decapsulate+0x7df/0x1e50 include/net/inet_ecn.h:321
__INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]
INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]
IP6_ECN_decapsulate+0x7df/0x1e50 include/net/inet_ecn.h:321
ip6ip6_dscp_ecn_decapsulate+0x178/0x1b0 net/ipv6/ip6_tunnel.c:727
__ip6_tnl_rcv+0xd4e/0x1590 net/ipv6/ip6_tunnel.c:845
ip6_tnl_rcv+0xce/0x100 net/ipv6/ip6_tunnel.c:888
gre_rcv+0x143f/0x1870
ip6_protocol_deliver_rcu+0xda6/0x2a60 net/ipv6/ip6_input.c:438
ip6_input_finish net/ipv6/ip6_input.c:483 [inline]
NF_HOOK include/linux/netfilter.h:314 [inline]
ip6_input+0x15d/0x430 net/ipv6/ip6_input.c:492
ip6_mc_input+0xa7e/0xc80 net/ipv6/ip6_input.c:586
dst_input include/net/dst.h:461 [inline]
ip6_rcv_finish+0x5db/0x870 net/ipv6/ip6_input.c:79
NF_HOOK include/linux/netfilter.h:314 [inline]
ipv6_rcv+0xda/0x390 net/ipv6/ip6_input.c:310
__netif_receive_skb_one_core net/core/dev.c:5532 [inline]
__netif_receive_sk...

Classification

CVE ID: CVE-2024-26641

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 12.41% (scored less or equal to compared to others)

EPSS Date: 2025-02-04 (when was this score calculated)

References

https://git.kernel.org/stable/c/a9bc32879a08f23cdb80a48c738017e39aea1080
https://git.kernel.org/stable/c/af6b5c50d47ab43e5272ad61935d0ed2e264d3f0
https://git.kernel.org/stable/c/d54e4da98bbfa8c257bdca94c49652d81d18a4d8
https://git.kernel.org/stable/c/350a6640fac4b53564ec20aa3f4a0922cb0ba5e6
https://git.kernel.org/stable/c/c835df3bcc14858ae9b27315dd7de76370b94f3a
https://git.kernel.org/stable/c/8d975c15c0cd744000ca386247432d57b21f9df0

Timeline