Bug 2297541 (CVE-2024-40957)

Summary: CVE-2024-40957 kernel: seg6: fix parameter passing when calling NF_HOOK() in End.DX4 and End.DX6 behaviors
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: kernel 5.15.162, kernel 6.1.96, kernel 6.6.36, kernel 6.9.7, kernel 6.10-rc5 Doc Type: If docs needed, set a value
Doc Text:
A vulnerability was found in the Linux kernel's segment routing (seg6) component in the input_action_end_dx4() and input_action_end_dx6() functions, where improper parameter passing to the NF_HOOK() can occur, which leads to a NULL pointer dereference when a NULL input device is provided, resulting in a kernel crash.
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Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2024-07-12 13:40:24 UTC
In the Linux kernel, the following vulnerability has been resolved:

seg6: fix parameter passing when calling NF_HOOK() in End.DX4 and End.DX6 behaviors

input_action_end_dx4() and input_action_end_dx6() are called NF_HOOK() for
PREROUTING hook, in PREROUTING hook, we should passing a valid indev,
and a NULL outdev to NF_HOOK(), otherwise may trigger a NULL pointer
dereference, as below:

    [74830.647293] BUG: kernel NULL pointer dereference, address: 0000000000000090
    [74830.655633] #PF: supervisor read access in kernel mode
    [74830.657888] #PF: error_code(0x0000) - not-present page
    [74830.659500] PGD 0 P4D 0
    [74830.660450] Oops: 0000 [#1] PREEMPT SMP PTI
    ...
    [74830.664953] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
    [74830.666569] RIP: 0010:rpfilter_mt+0x44/0x15e [ipt_rpfilter]
    ...
    [74830.689725] Call Trace:
    [74830.690402]  <IRQ>
    [74830.690953]  ? show_trace_log_lvl+0x1c4/0x2df
    [74830.692020]  ? show_trace_log_lvl+0x1c4/0x2df
    [74830.693095]  ? ipt_do_table+0x286/0x710 [ip_tables]
    [74830.694275]  ? __die_body.cold+0x8/0xd
    [74830.695205]  ? page_fault_oops+0xac/0x140
    [74830.696244]  ? exc_page_fault+0x62/0x150
    [74830.697225]  ? asm_exc_page_fault+0x22/0x30
    [74830.698344]  ? rpfilter_mt+0x44/0x15e [ipt_rpfilter]
    [74830.699540]  ipt_do_table+0x286/0x710 [ip_tables]
    [74830.700758]  ? ip6_route_input+0x19d/0x240
    [74830.701752]  nf_hook_slow+0x3f/0xb0
    [74830.702678]  input_action_end_dx4+0x19b/0x1e0
    [74830.703735]  ? input_action_end_t+0xe0/0xe0
    [74830.704734]  seg6_local_input_core+0x2d/0x60
    [74830.705782]  lwtunnel_input+0x5b/0xb0
    [74830.706690]  __netif_receive_skb_one_core+0x63/0xa0
    [74830.707825]  process_backlog+0x99/0x140
    [74830.709538]  __napi_poll+0x2c/0x160
    [74830.710673]  net_rx_action+0x296/0x350
    [74830.711860]  __do_softirq+0xcb/0x2ac
    [74830.713049]  do_softirq+0x63/0x90

input_action_end_dx4() passing a NULL indev to NF_HOOK(), and finally
trigger a NULL dereference in rpfilter_mt()->rpfilter_is_loopback():

    static bool
    rpfilter_is_loopback(const struct sk_buff *skb,
          	       const struct net_device *in)
    {
            // in is NULL
            return skb->pkt_type == PACKET_LOOPBACK ||
          	 in->flags & IFF_LOOPBACK;
    }

Comment 5 errata-xmlrpc 2024-08-28 12:21:05 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2024:5928 https://access.redhat.com/errata/RHSA-2024:5928