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.
[
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"net/tipc/msg.c"
],
"versions": [
{
"version": "45c8b7b175ce",
"lessThan": "b2c8d28c34b3",
"status": "affected",
"versionType": "git"
},
{
"version": "45c8b7b175ce",
"lessThan": "5489f30bb78f",
"status": "affected",
"versionType": "git"
},
{
"version": "45c8b7b175ce",
"lessThan": "436d650d3743",
"status": "affected",
"versionType": "git"
},
{
"version": "45c8b7b175ce",
"lessThan": "4b1761898861",
"status": "affected",
"versionType": "git"
},
{
"version": "45c8b7b175ce",
"lessThan": "64d17ec9f1de",
"status": "affected",
"versionType": "git"
},
{
"version": "45c8b7b175ce",
"lessThan": "6da24cfc83ba",
"status": "affected",
"versionType": "git"
},
{
"version": "45c8b7b175ce",
"lessThan": "ace300eecbcc",
"status": "affected",
"versionType": "git"
},
{
"version": "45c8b7b175ce",
"lessThan": "b7df21cf1b79",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"net/tipc/msg.c"
],
"versions": [
{
"version": "4.3",
"status": "affected"
},
{
"version": "0",
"lessThan": "4.3",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "4.4.271",
"lessThanOrEqual": "4.4.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "4.9.271",
"lessThanOrEqual": "4.9.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "4.14.235",
"lessThanOrEqual": "4.14.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "4.19.193",
"lessThanOrEqual": "4.19.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.4.124",
"lessThanOrEqual": "5.4.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.10.42",
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.12.9",
"lessThanOrEqual": "5.12.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.13",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
]
git.kernel.org/stable/c/436d650d374329a591c30339a91fa5078052ed1e
git.kernel.org/stable/c/4b1761898861117c97066aea6c58f68a7787f0bf
git.kernel.org/stable/c/5489f30bb78ff0dafb4229a69632afc2ba20765c
git.kernel.org/stable/c/64d17ec9f1ded042c4b188d15734f33486ed9966
git.kernel.org/stable/c/6da24cfc83ba4f97ea44fc7ae9999a006101755c
git.kernel.org/stable/c/ace300eecbccaa698e2b472843c74a5f33f7dce8
git.kernel.org/stable/c/b2c8d28c34b3070407cb1741f9ba3f15d0284b8b
git.kernel.org/stable/c/b7df21cf1b79ab7026f545e7bf837bd5750ac026