CVE-2023-52906: In the Linux kernel, the following vulnerability has been resolved: net/sched: act_mpls: Fix warning during failed attribute validation The 'TCA_MPL...

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_mpls: Fix warning during failed attribute validation The 'TCA_MPLS_LABEL' attribute is of 'NLA_U32' type, but has a validation type of 'NLA_VALIDATE_FUNCTION'. This is an invalid combination according to the comment above 'struct nla_policy': " Meaning of `validate' field, use via NLA_POLICY_VALIDATE_FN: NLA_BINARY Validation function called for the attribute. All other Unused - but note that it's a union " This can trigger the warning [1] in nla_get_range_unsigned() when validation of the attribute fails. Despite being of 'NLA_U32' type, the associated 'min'/'max' fields in the policy are negative as they are aliased by the 'validate' field. Fix by changing the attribute type to 'NLA_BINARY' which is consistent with the above comment and all other users of NLA_POLICY_VALIDATE_FN(). As a result, move the length validation to the validation function. No regressions in MPLS tests: # ./tdc.py -f tc-tests/actions/mpls.json [...] # echo $? 0 [1] WARNING: CPU: 0 PID: 17743 at lib/nlattr.c:118 nla_get_range_unsigned+0x1d8/0x1e0 lib/nlattr.c:117 Modules linked in: CPU: 0 PID: 17743 Comm: syz-executor.0 Not tainted 6.1.0-rc8 #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014 RIP: 0010:nla_get_range_unsigned+0x1d8/0x1e0 lib/nlattr.c:117 [...] Call Trace: <TASK> __netlink_policy_dump_write_attr+0x23d/0x990 net/netlink/policy.c:310 netlink_policy_dump_write_attr+0x22/0x30 net/netlink/policy.c:411 netlink_ack_tlv_fill net/netlink/af_netlink.c:2454 [inline] netlink_ack+0x546/0x760 net/netlink/af_netlink.c:2506 netlink_rcv_skb+0x1b7/0x240 net/netlink/af_netlink.c:2546 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:6109 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x5e9/0x6b0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x739/0x860 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0x38f/0x500 net/socket.c:2482 ___sys_sendmsg net/socket.c:2536 [inline] __sys_sendmsg+0x197/0x230 net/socket.c:2565 __do_sys_sendmsg net/socket.c:2574 [inline] __se_sys_sendmsg net/socket.c:2572 [inline] __x64_sys_sendmsg+0x42/0x50 net/socket.c:2572 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.25%

16.0th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions	Update
Linux	Linux Kernel	>= 5.3, < 5.4.229	—
Linux	Linux Kernel	>= 5.5, < 5.10.164	—
Linux	Linux Kernel	>= 5.11, < 5.15.89	—
Linux	Linux Kernel	>= 5.16, < 6.1.7	—
Linux	Linux Kernel	6.2	Rc1

References

Timeline

Published: Aug 21, 2024
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2023-52906?

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_mpls: Fix warning during failed attribute validation The 'TCA_MPLS_LABEL' attribute is of 'NLA_U32' type, but has a validation type of 'NLA_VALIDATE_FUNCTION'. This is an invalid combination according to the comment above 'struct nla_policy': " Meaning of `validate' field, use via NLA_POLICY_VALIDATE_FN: NLA_BINARY Validation function called for the attribute. All other Unused - but note that it's a union " This can trigger the warning [1] in nla_get_range_unsigned() when validation of the attribute fails. Despite being of 'NLA_U32' type, the associated 'min'/'max' fields in the policy are negative as they are aliased by the 'validate' field. Fix by changing the attribute type to 'NLA_BINARY' which is consistent with the above comment and all other users of NLA_POLICY_VALIDATE_FN(). As a result, move the length validation to the validation function. No regressions in MPLS tests: # ./tdc.py -f tc-tests/actions/mpls.json [...] # echo $? 0 [1] WARNING: CPU: 0 PID: 17743 at lib/nlattr.c:118 nla_get_range_unsigned+0x1d8/0x1e0 lib/nlattr.c:117 Modules linked in: CPU: 0 PID: 17743 Comm: syz-executor.0 Not tainted 6.1.0-rc8 #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014 RIP: 0010:nla_get_range_unsigned+0x1d8/0x1e0 lib/nlattr.c:117 [...] Call Trace: <TASK> __netlink_policy_dump_write_attr+0x23d/0x990 net/netlink/policy.c:310 netlink_policy_dump_write_attr+0x22/0x30 net/netlink/policy.c:411 netlink_ack_tlv_fill net/netlink/af_netlink.c:2454 [inline] netlink_ack+0x546/0x760 net/netlink/af_netlink.c:2506 netlink_rcv_skb+0x1b7/0x240 net/netlink/af_netlink.c:2546 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:6109 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x5e9/0x6b0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x739/0x860 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0x38f/0x500 net/socket.c:2482 ___sys_sendmsg net/socket.c:2536 [inline] __sys_sendmsg+0x197/0x230 net/socket.c:2565 __do_sys_sendmsg net/socket.c:2574 [inline] __se_sys_sendmsg net/socket.c:2572 [inline] __x64_sys_sendmsg+0x42/0x50 net/socket.c:2572 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd

How severe is CVE-2023-52906?

CVE-2023-52906 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.25% probability of exploitation in the next 30 days.

How do I fix CVE-2023-52906?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.