Linux Kernel up to 6.6.14/6.7.2 tcf_block_offload_unbind memory leak

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 6.6.14/6.7.2. Impacted is the function tcf_block_offload_unbind. This manipulation causes memory leak. This vulnerability is tracked as CVE-2024-26669. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.6.14/6.7.2. Affected by this vulnerability is the function tcf_block_offload_unbind. The manipulation with an unknown input leads to a memory leak vulnerability. The CWE definition for the vulnerability is CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: net/sched: flower: Fix chain template offload When a qdisc is deleted from a net device the stack instructs the underlying driver to remove its flow offload callback from the associated filter block using the 'FLOW_BLOCK_UNBIND' command. The stack then continues to replay the removal of the filters in the block for this driver by iterating over the chains in the block and invoking the 'reoffload' operation of the classifier being used. In turn, the classifier in its 'reoffload' operation prepares and emits a 'FLOW_CLS_DESTROY' command for each filter. However, the stack does not do the same for chain templates and the underlying driver never receives a 'FLOW_CLS_TMPLT_DESTROY' command when a qdisc is deleted. This results in a memory leak [1] which can be reproduced using [2]. Fix by introducing a 'tmplt_reoffload' operation and have the stack invoke it with the appropriate arguments as part of the replay. Implement the operation in the sole classifier that supports chain templates (flower) by emitting the 'FLOW_CLS_TMPLT_{CREATE,DESTROY}' command based on whether a flow offload callback is being bound to a filter block or being unbound from one. As far as I can tell, the issue happens since cited commit which reordered tcf_block_offload_unbind() before tcf_block_flush_all_chains() in __tcf_block_put(). The order cannot be reversed as the filter block is expected to be freed after flushing all the chains. [1] unreferenced object 0xffff888107e28800 (size 2048): comm "tc", pid 1079, jiffies 4294958525 (age 3074.287s) hex dump (first 32 bytes): b1 a6 7c 11 81 88 ff ff e0 5b b3 10 81 88 ff ff ..|......[...... 01 00 00 00 00 00 00 00 e0 aa b0 84 ff ff ff ff ................ backtrace: [] __kmem_cache_alloc_node+0x1e8/0x320 [] __kmalloc+0x4e/0x90 [] mlxsw_sp_acl_ruleset_get+0x34d/0x7a0 [] mlxsw_sp_flower_tmplt_create+0x145/0x180 [] mlxsw_sp_flow_block_cb+0x1ea/0x280 [] tc_setup_cb_call+0x183/0x340 [] fl_tmplt_create+0x3da/0x4c0 [] tc_ctl_chain+0xa15/0x1170 [] rtnetlink_rcv_msg+0x3cc/0xed0 [] netlink_rcv_skb+0x170/0x440 [] netlink_unicast+0x540/0x820 [] netlink_sendmsg+0x8d8/0xda0 [] ____sys_sendmsg+0x30f/0xa80 [] ___sys_sendmsg+0x13a/0x1e0 [] __sys_sendmsg+0x11c/0x1f0 [] do_syscall_64+0x40/0xe0 unreferenced object 0xffff88816d2c0400 (size 1024): comm "tc", pid 1079, jiffies 4294958525 (age 3074.287s) hex dump (first 32 bytes): 40 00 00 00 00 00 00 00 57 f6 38 be 00 00 00 00 @.......W.8..... 10 04 2c 6d 81 88 ff ff 10 04 2c 6d 81 88 ff ff ..,m......,m.... backtrace: [] __kmem_cache_alloc_node+0x1e8/0x320 [] __kmalloc_node+0x51/0x90 [] kvmalloc_node+0xa6/0x1f0 [] bucket_table_alloc.isra.0+0x83/0x460 [] rhashtable_init+0x43b/0x7c0 [] mlxsw_sp_acl_ruleset_get+0x428/0x7a0 [] mlxsw_sp_flower_tmplt_create+0x145/0x180 [] mlxsw_sp_flow_block_cb+0x1ea/0x280 [] tc_setup_cb_call+0x183/0x340 [] fl_tmplt_create+0x3da/0x4c0 [] tc_ctl_chain+0xa15/0x1170 [] rtnetlink_rcv_msg+0x3cc/0xed0 [] netlink_rcv_skb+0x170/0x440 [] netlink_unicast+0x540/0x820 [] netlink_sendmsg+0x8d8/0xda0 [] ____sys_sendmsg+0x30f/0xa80 [2] # tc qdisc add dev swp1 clsact # tc chain add dev swp1 ingress proto ip chain 1 flower dst_ip 0.0.0.0/32 # tc qdisc del dev ---truncated---

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2024-26669 since 02/19/2024. The exploitation appears to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 207884 (openSUSE 15 Security Update : kernel (SUSE-SU-2024:3483-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.15, 6.7.3 or 6.8 eliminates this vulnerability. Applying the patch 9ed46144cff3/c04709b2cc99/32f2a0afa95f is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (207884) and CERT Bund (WID-SEC-2025-1293). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Ubuntu Linux
• IBM DataPower Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.6.0
• 6.6.1
• 6.6.2
• 6.6.3
• 6.6.4
• 6.6.5
• 6.6.6
• 6.6.7
• 6.6.8
• 6.6.9
• 6.6.10
• 6.6.11
• 6.6.12
• 6.6.13
• 6.6.14
• 6.7.0
• 6.7.1
• 6.7.2

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Exploitinginfo

Threat Intelligenceinfo

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Entryinfo

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