CVE-2024-43834

Published Aug 17, 2024

Last updated a month ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: xdp: fix invalid wait context of page_pool_destroy() If the driver uses a page pool, it creates a page pool with page_pool_create(). The reference count of page pool is 1 as default. A page pool will be destroyed only when a reference count reaches 0. page_pool_destroy() is used to destroy page pool, it decreases a reference count. When a page pool is destroyed, ->disconnect() is called, which is mem_allocator_disconnect(). This function internally acquires mutex_lock(). If the driver uses XDP, it registers a memory model with xdp_rxq_info_reg_mem_model(). The xdp_rxq_info_reg_mem_model() internally increases a page pool reference count if a memory model is a page pool. Now the reference count is 2. To destroy a page pool, the driver should call both page_pool_destroy() and xdp_unreg_mem_model(). The xdp_unreg_mem_model() internally calls page_pool_destroy(). Only page_pool_destroy() decreases a reference count. If a driver calls page_pool_destroy() then xdp_unreg_mem_model(), we will face an invalid wait context warning. Because xdp_unreg_mem_model() calls page_pool_destroy() with rcu_read_lock(). The page_pool_destroy() internally acquires mutex_lock(). Splat looks like: ============================= [ BUG: Invalid wait context ] 6.10.0-rc6+ #4 Tainted: G W ----------------------------- ethtool/1806 is trying to lock: ffffffff90387b90 (mem_id_lock){+.+.}-{4:4}, at: mem_allocator_disconnect+0x73/0x150 other info that might help us debug this: context-{5:5} 3 locks held by ethtool/1806: stack backtrace: CPU: 0 PID: 1806 Comm: ethtool Tainted: G W 6.10.0-rc6+ #4 f916f41f172891c800f2fed Hardware name: ASUS System Product Name/PRIME Z690-P D4, BIOS 0603 11/01/2021 Call Trace: <TASK> dump_stack_lvl+0x7e/0xc0 __lock_acquire+0x1681/0x4de0 ? _printk+0x64/0xe0 ? __pfx_mark_lock.part.0+0x10/0x10 ? __pfx___lock_acquire+0x10/0x10 lock_acquire+0x1b3/0x580 ? mem_allocator_disconnect+0x73/0x150 ? __wake_up_klogd.part.0+0x16/0xc0 ? __pfx_lock_acquire+0x10/0x10 ? dump_stack_lvl+0x91/0xc0 __mutex_lock+0x15c/0x1690 ? mem_allocator_disconnect+0x73/0x150 ? __pfx_prb_read_valid+0x10/0x10 ? mem_allocator_disconnect+0x73/0x150 ? __pfx_llist_add_batch+0x10/0x10 ? console_unlock+0x193/0x1b0 ? lockdep_hardirqs_on+0xbe/0x140 ? __pfx___mutex_lock+0x10/0x10 ? tick_nohz_tick_stopped+0x16/0x90 ? __irq_work_queue_local+0x1e5/0x330 ? irq_work_queue+0x39/0x50 ? __wake_up_klogd.part.0+0x79/0xc0 ? mem_allocator_disconnect+0x73/0x150 mem_allocator_disconnect+0x73/0x150 ? __pfx_mem_allocator_disconnect+0x10/0x10 ? mark_held_locks+0xa5/0xf0 ? rcu_is_watching+0x11/0xb0 page_pool_release+0x36e/0x6d0 page_pool_destroy+0xd7/0x440 xdp_unreg_mem_model+0x1a7/0x2a0 ? __pfx_xdp_unreg_mem_model+0x10/0x10 ? kfree+0x125/0x370 ? bnxt_free_ring.isra.0+0x2eb/0x500 ? bnxt_free_mem+0x5ac/0x2500 xdp_rxq_info_unreg+0x4a/0xd0 bnxt_free_mem+0x1356/0x2500 bnxt_close_nic+0xf0/0x3b0 ? __pfx_bnxt_close_nic+0x10/0x10 ? ethnl_parse_bit+0x2c6/0x6d0 ? __pfx___nla_validate_parse+0x10/0x10 ? __pfx_ethnl_parse_bit+0x10/0x10 bnxt_set_features+0x2a8/0x3e0 __netdev_update_features+0x4dc/0x1370 ? ethnl_parse_bitset+0x4ff/0x750 ? __pfx_ethnl_parse_bitset+0x10/0x10 ? __pfx___netdev_update_features+0x10/0x10 ? mark_held_locks+0xa5/0xf0 ? _raw_spin_unlock_irqrestore+0x42/0x70 ? __pm_runtime_resume+0x7d/0x110 ethnl_set_features+0x32d/0xa20 To fix this problem, it uses rhashtable_lookup_fast() instead of rhashtable_lookup() with rcu_read_lock(). Using xa without rcu_read_lock() here is safe. xa is freed by __xdp_mem_allocator_rcu_free() and this is called by call_rcu() of mem_xa_remove(). The mem_xa_remove() is called by page_pool_destroy() if a reference count reaches 0. The xa is already protected by the reference count mechanism well in the control plane. So removing rcu_read_lock() for page_pool_destroy() is safe.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
NVD-CWE-noinfo

Social media

Hype score
Not currently trending

Configurations

  1. In the Linux kernel, the following vulnerability has been resolved: coresight: tmc-etr: Fix race condition between sysfs and perf mode When trying to run perf and sysfs mode simultaneously, the WARN_ON() in tmc_etr_enable_hw() is triggered sometimes: WARNING: CPU: 42 PID: 3911571 at drivers/hwtracing/coresight/coresight-tmc-etr.c:1060 tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] [..snip..] Call trace: tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] (P) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] (L) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] coresight_enable_path+0x1c8/0x218 [coresight] coresight_enable_sysfs+0xa4/0x228 [coresight] enable_source_store+0x58/0xa8 [coresight] dev_attr_store+0x20/0x40 sysfs_kf_write+0x4c/0x68 kernfs_fop_write_iter+0x120/0x1b8 vfs_write+0x2c8/0x388 ksys_write+0x74/0x108 __arm64_sys_write+0x24/0x38 el0_svc_common.constprop.0+0x64/0x148 do_el0_svc+0x24/0x38 el0_svc+0x3c/0x130 el0t_64_sync_handler+0xc8/0xd0 el0t_64_sync+0x1ac/0x1b0 ---[ end trace 0000000000000000 ]--- Since the enablement of sysfs mode is separeted into two critical regions, one for sysfs buffer allocation and another for hardware enablement, it's possible to race with the perf mode. Fix this by double check whether the perf mode's been used before enabling the hardware in sysfs mode. mode: [sysfs mode] [perf mode] tmc_etr_get_sysfs_buffer() spin_lock(&drvdata->spinlock) [sysfs buffer allocation] spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() drvdata->etr_buf = etr_perf->etr_buf spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() WARN_ON(drvdata->etr_buf) // WARN sicne etr_buf initialized at the perf side spin_unlock(&drvdata->spinlock) With this fix, we retain the check for CS_MODE_PERF in get_etr_sysfs_buf. This ensures we verify whether the perf mode's already running before we actually allocate the buffer. Then we can save the time of allocating/freeing the sysfs buffer if race with the perf mode.CVE-2026-46272