Bug 2320729 (CVE-2022-48974)

Summary: CVE-2022-48974 kernel: netfilter: conntrack: fix using __this_cpu_add in preemptible
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2024-10-21 21:05:30 UTC
In the Linux kernel, the following vulnerability has been resolved:

netfilter: conntrack: fix using __this_cpu_add in preemptible

Currently in nf_conntrack_hash_check_insert(), when it fails in
nf_ct_ext_valid_pre/post(), NF_CT_STAT_INC() will be called in the
preemptible context, a call trace can be triggered:

   BUG: using __this_cpu_add() in preemptible [00000000] code: conntrack/1636
   caller is nf_conntrack_hash_check_insert+0x45/0x430 [nf_conntrack]
   Call Trace:
    <TASK>
    dump_stack_lvl+0x33/0x46
    check_preemption_disabled+0xc3/0xf0
    nf_conntrack_hash_check_insert+0x45/0x430 [nf_conntrack]
    ctnetlink_create_conntrack+0x3cd/0x4e0 [nf_conntrack_netlink]
    ctnetlink_new_conntrack+0x1c0/0x450 [nf_conntrack_netlink]
    nfnetlink_rcv_msg+0x277/0x2f0 [nfnetlink]
    netlink_rcv_skb+0x50/0x100
    nfnetlink_rcv+0x65/0x144 [nfnetlink]
    netlink_unicast+0x1ae/0x290
    netlink_sendmsg+0x257/0x4f0
    sock_sendmsg+0x5f/0x70

This patch is to fix it by changing to use NF_CT_STAT_INC_ATOMIC() for
nf_ct_ext_valid_pre/post() check in nf_conntrack_hash_check_insert(),
as well as nf_ct_ext_valid_post() in __nf_conntrack_confirm().

Note that nf_ct_ext_valid_pre() check in __nf_conntrack_confirm() is
safe to use NF_CT_STAT_INC(), as it's under local_bh_disable().

Comment 1 Avinash Hanwate 2024-10-22 06:27:27 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024102145-CVE-2022-48974-d2d0@gregkh/T