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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2021-47162 Detail

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

 
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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
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References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://git.kernel.org/stable/c/436d650d374329a591c30339a91fa5078052ed1e CVE, kernel.org Patch 
https://git.kernel.org/stable/c/4b1761898861117c97066aea6c58f68a7787f0bf CVE, kernel.org Patch 
https://git.kernel.org/stable/c/5489f30bb78ff0dafb4229a69632afc2ba20765c CVE, kernel.org Patch 
https://git.kernel.org/stable/c/64d17ec9f1ded042c4b188d15734f33486ed9966 CVE, kernel.org Patch 
https://git.kernel.org/stable/c/6da24cfc83ba4f97ea44fc7ae9999a006101755c CVE, kernel.org Patch 
https://git.kernel.org/stable/c/ace300eecbccaa698e2b472843c74a5f33f7dce8 CVE, kernel.org Patch 
https://git.kernel.org/stable/c/b2c8d28c34b3070407cb1741f9ba3f15d0284b8b CVE, kernel.org Patch 
https://git.kernel.org/stable/c/b7df21cf1b79ab7026f545e7bf837bd5750ac026 CVE, kernel.org Patch 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-416 Use After Free cwe source acceptance level NIST  

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Change History

5 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2021-47162
NVD Published Date:
03/25/2024
NVD Last Modified:
03/13/2025
Source:
kernel.org