xfrm: fix ip_rt_bug race in icmp_route_lookup reverse path
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Linux | Linux | affected |
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Configuration 1 [-]
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| Source | ID | Title |
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Ubuntu USN |
USN-8492-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-8492-2 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-8497-1 | Linux kernel (Low Latency) vulnerabilities |
Ubuntu USN |
USN-8498-1 | Linux kernel (NVIDIA Tegra) vulnerabilities |
Ubuntu USN |
USN-8499-1 | Linux kernel (Xilinx) vulnerabilities |
Ubuntu USN |
USN-8492-3 | Linux kernel (Raspberry Pi Real-time) vulnerabilities |
Ubuntu USN |
USN-8492-4 | Linux kernel (Raspberry Pi) vulnerabilities |
Ubuntu USN |
USN-8492-5 | Linux kernel (FIPS) vulnerabilities |
Ubuntu USN |
USN-8606-1 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-8607-1 | Linux kernel (Azure CVM) vulnerabilities |
Ubuntu USN |
USN-8609-1 | Linux kernel (Azure CVM) vulnerabilities |
Ubuntu USN |
USN-8619-1 | Linux kernel (HWE) vulnerabilities |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.111% probability within 30 days)
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ssvc
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| Weaknesses | CWE-362 |
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| Weaknesses | CWE-367 | |
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threat_severity
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cvssV3_1
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| Weaknesses | CWE-362 |
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| Description | In the Linux kernel, the following vulnerability has been resolved: xfrm: fix ip_rt_bug race in icmp_route_lookup reverse path icmp_route_lookup() performs multiple route lookups to find a suitable route for sending ICMP error messages, with special handling for XFRM (IPsec) policies. The lookup sequence is: 1. First, lookup output route for ICMP reply (dst = original src) 2. Pass through xfrm_lookup() for policy check 3. If blocked (-EPERM) or dst is not local, enter "reverse path" 4. In reverse path, call xfrm_decode_session_reverse() to get fl4_dec which reverses the original packet's flow (saddr<->daddr swapped) 5. If fl4_dec.saddr is local (we are the original destination), use __ip_route_output_key() for output route lookup 6. If fl4_dec.saddr is NOT local (we are a forwarding node), use ip_route_input() to simulate the reverse packet's input path 7. Finally, pass rt2 through xfrm_lookup() with XFRM_LOOKUP_ICMP flag The bug occurs in step 6: ip_route_input() is called with fl4_dec.daddr (original packet's source) as destination. If this address becomes local between the initial check and ip_route_input() call (e.g., due to concurrent "ip addr add"), ip_route_input() returns a LOCAL route with dst.output set to ip_rt_bug. This route is then used for ICMP output, causing dst_output() to call ip_rt_bug(), triggering a WARN_ON: ------------[ cut here ]------------ WARNING: net/ipv4/route.c:1275 at ip_rt_bug+0x21/0x30, CPU#1 Call Trace: <TASK> ip_push_pending_frames+0x202/0x240 icmp_push_reply+0x30d/0x430 __icmp_send+0x1149/0x24f0 ip_options_compile+0xa2/0xd0 ip_rcv_finish_core+0x829/0x1950 ip_rcv+0x2d7/0x420 __netif_receive_skb_one_core+0x185/0x1f0 netif_receive_skb+0x90/0x450 tun_get_user+0x3413/0x3fb0 tun_chr_write_iter+0xe4/0x220 ... Fix this by checking rt2->rt_type after ip_route_input(). If it's RTN_LOCAL, the route cannot be used for output, so treat it as an error. The reproducer requires kernel modification to widen the race window, making it unsuitable as a selftest. It is available at: https://gist.github.com/mrpre/eae853b72ac6a750f5d45d64ddac1e81 | |
| Title | xfrm: fix ip_rt_bug race in icmp_route_lookup reverse path | |
| First Time appeared |
Linux
Linux linux Kernel |
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| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
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| References |
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