Description

In the Linux kernel, the following vulnerability has been resolved: tipc: skb_linearize the head skb when reassembling msgs It's not a good idea to append the frag skb to a skb's frag_list if the frag_list already has skbs from elsewhere, such as this skb was created by pskb_copy() where the frag_list was cloned (all the skbs in it were skb_get'ed) and shared by multiple skbs. However, the new appended frag skb should have been only seen by the current skb. Otherwise, it will cause use after free crashes as this appended frag skb are seen by multiple skbs but it only got skb_get called once. The same thing happens with a skb updated by pskb_may_pull() with a skb_cloned skb. Li Shuang has reported quite a few crashes caused by this when doing testing over macvlan devices: [] kernel BUG at net/core/skbuff.c:1970! [] Call Trace: [] skb_clone+0x4d/0xb0 [] macvlan_broadcast+0xd8/0x160 [macvlan] [] macvlan_process_broadcast+0x148/0x150 [macvlan] [] process_one_work+0x1a7/0x360 [] worker_thread+0x30/0x390 [] kernel BUG at mm/usercopy.c:102! [] Call Trace: [] __check_heap_object+0xd3/0x100 [] __check_object_size+0xff/0x16b [] simple_copy_to_iter+0x1c/0x30 [] __skb_datagram_iter+0x7d/0x310 [] __skb_datagram_iter+0x2a5/0x310 [] skb_copy_datagram_iter+0x3b/0x90 [] tipc_recvmsg+0x14a/0x3a0 [tipc] [] ____sys_recvmsg+0x91/0x150 [] ___sys_recvmsg+0x7b/0xc0 [] kernel BUG at mm/slub.c:305! [] Call Trace: [] <IRQ> [] kmem_cache_free+0x3ff/0x400 [] __netif_receive_skb_core+0x12c/0xc40 [] ? kmem_cache_alloc+0x12e/0x270 [] netif_receive_skb_internal+0x3d/0xb0 [] ? get_rx_page_info+0x8e/0xa0 [be2net] [] be_poll+0x6ef/0xd00 [be2net] [] ? irq_exit+0x4f/0x100 [] net_rx_action+0x149/0x3b0 ... This patch is to fix it by linearizing the head skb if it has frag_list set in tipc_buf_append(). Note that we choose to do this before calling skb_unshare(), as __skb_linearize() will avoid skb_copy(). Also, we can not just drop the frag_list either as the early time.

Metrics

 

CVSS Version 4.0 CVSS Version 3.x CVSS Version 2.0

NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.

CVSS 4.0 Severity and Vector Strings:

NIST: NVD

N/A

NVD assessment not yet provided.

CVSS 3.x Severity and Vector Strings:

NIST: NVD

Base Score:  N/A

NVD assessment not yet provided.

CVSS 2.0 Severity and Vector Strings:

NIST: NVD

Base Score: N/A

NVD assessment not yet provided.

https://git.kernel.org/stable/c/436d650d374329a591c30339a91fa5078052ed1e

https://git.kernel.org/stable/c/4b1761898861117c97066aea6c58f68a7787f0bf

https://git.kernel.org/stable/c/5489f30bb78ff0dafb4229a69632afc2ba20765c

https://git.kernel.org/stable/c/64d17ec9f1ded042c4b188d15734f33486ed9966

https://git.kernel.org/stable/c/6da24cfc83ba4f97ea44fc7ae9999a006101755c

https://git.kernel.org/stable/c/ace300eecbccaa698e2b472843c74a5f33f7dce8

https://git.kernel.org/stable/c/b2c8d28c34b3070407cb1741f9ba3f15d0284b8b

https://git.kernel.org/stable/c/b7df21cf1b79ab7026f545e7bf837bd5750ac026

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

tipc: skb_linearize the head skb when reassembling msgs

It's not a good idea to append the frag skb to a skb's frag_list if
the frag_list already has skbs from elsewhere, such as this skb was
created by pskb_copy() where the frag_list was cloned (all the skbs
in it were skb_get'ed) and shared by multiple skbs.

However, the new appended frag skb should have been only seen by the
current skb. Otherwise, it will cause use after 

kernel.org https://git.kernel.org/stable/c/436d650d374329a591c30339a91fa5078052ed1e [No types assigned]

kernel.org https://git.kernel.org/stable/c/4b1761898861117c97066aea6c58f68a7787f0bf [No types assigned]

kernel.org https://git.kernel.org/stable/c/5489f30bb78ff0dafb4229a69632afc2ba20765c [No types assigned]

kernel.org https://git.kernel.org/stable/c/64d17ec9f1ded042c4b188d15734f33486ed9966 [No types assigned]

kernel.org https://git.kernel.org/stable/c/6da24cfc83ba4f97ea44fc7ae9999a006101755c [No types assigned]

kernel.org https://git.kernel.org/stable/c/ace300eecbccaa698e2b472843c74a5f33f7dce8 [No types assigned]

kernel.org https://git.kernel.org/stable/c/b2c8d28c34b3070407cb1741f9ba3f15d0284b8b [No types assigned]

kernel.org https://git.kernel.org/stable/c/b7df21cf1b79ab7026f545e7bf837bd5750ac026 [No types assigned]