CVE-2021-47387 cpufreq: schedutil: Use kobject release() method to free sugov_tunables

2024-05-2115:03:46

Linux

github.com

linux kernel

vulnerability resolved

cpufreq

schedutil

kobject

sugov_tunables

call trace

marvell octeontx

cpu

pid

struct sugov_tunables

kobject release()

cve

6.9 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

10.4%

JSON

In the Linux kernel, the following vulnerability has been resolved:

cpufreq: schedutil: Use kobject release() method to free sugov_tunables

The struct sugov_tunables is protected by the kobject, so we can’t free
it directly. Otherwise we would get a call trace like this:
ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x30
WARNING: CPU: 3 PID: 720 at lib/debugobjects.c:505 debug_print_object+0xb8/0x100
Modules linked in:
CPU: 3 PID: 720 Comm: a.sh Tainted: G W 5.14.0-rc1-next-20210715-yocto-standard+ #507
Hardware name: Marvell OcteonTX CN96XX board (DT)
pstate: 40400009 (nZcv daif +PAN -UAO -TCO BTYPE=–)
pc : debug_print_object+0xb8/0x100
lr : debug_print_object+0xb8/0x100
sp : ffff80001ecaf910
x29: ffff80001ecaf910 x28: ffff00011b10b8d0 x27: ffff800011043d80
x26: ffff00011a8f0000 x25: ffff800013cb3ff0 x24: 0000000000000000
x23: ffff80001142aa68 x22: ffff800011043d80 x21: ffff00010de46f20
x20: ffff800013c0c520 x19: ffff800011d8f5b0 x18: 0000000000000010
x17: 6e6968207473696c x16: 5f72656d6974203a x15: 6570797420746365
x14: 6a626f2029302065 x13: 303378302f307830 x12: 2b6e665f72656d69
x11: ffff8000124b1560 x10: ffff800012331520 x9 : ffff8000100ca6b0
x8 : 000000000017ffe8 x7 : c0000000fffeffff x6 : 0000000000000001
x5 : ffff800011d8c000 x4 : ffff800011d8c740 x3 : 0000000000000000
x2 : ffff0001108301c0 x1 : ab3c90eedf9c0f00 x0 : 0000000000000000
Call trace:
debug_print_object+0xb8/0x100
__debug_check_no_obj_freed+0x1c0/0x230
debug_check_no_obj_freed+0x20/0x88
slab_free_freelist_hook+0x154/0x1c8
kfree+0x114/0x5d0
sugov_exit+0xbc/0xc0
cpufreq_exit_governor+0x44/0x90
cpufreq_set_policy+0x268/0x4a8
store_scaling_governor+0xe0/0x128
store+0xc0/0xf0
sysfs_kf_write+0x54/0x80
kernfs_fop_write_iter+0x128/0x1c0
new_sync_write+0xf0/0x190
vfs_write+0x2d4/0x478
ksys_write+0x74/0x100
__arm64_sys_write+0x24/0x30
invoke_syscall.constprop.0+0x54/0xe0
do_el0_svc+0x64/0x158
el0_svc+0x2c/0xb0
el0t_64_sync_handler+0xb0/0xb8
el0t_64_sync+0x198/0x19c
irq event stamp: 5518
hardirqs last enabled at (5517): [<ffff8000100cbd7c>] console_unlock+0x554/0x6c8
hardirqs last disabled at (5518): [<ffff800010fc0638>] el1_dbg+0x28/0xa0
softirqs last enabled at (5504): [<ffff8000100106e0>] __do_softirq+0x4d0/0x6c0
softirqs last disabled at (5483): [<ffff800010049548>] irq_exit+0x1b0/0x1b8

So split the original sugov_tunables_free() into two functions,
sugov_clear_global_tunables() is just used to clear the global_tunables
and the new sugov_tunables_free() is used as kobj_type::release to
release the sugov_tunables safely.

CNA Affected

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "9bdcb44e391d",
        "lessThan": "cb4a53ba3753",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "9bdcb44e391d",
        "lessThan": "463c46705f32",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "9bdcb44e391d",
        "lessThan": "30d57cf2c411",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "9bdcb44e391d",
        "lessThan": "67c98e023135",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "9bdcb44e391d",
        "lessThan": "a7d4fc84404d",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "9bdcb44e391d",
        "lessThan": "8d62aec52a8c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "9bdcb44e391d",
        "lessThan": "e5c6b312ce3c",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "kernel/sched/cpufreq_schedutil.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.7"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.7",
        "versionType": "custom"
      },
      {
        "status": "unaffected",
        "version": "4.9.285",
        "versionType": "custom",
        "lessThanOrEqual": "4.9.*"
      },
      {
        "status": "unaffected",
        "version": "4.14.249",
        "versionType": "custom",
        "lessThanOrEqual": "4.14.*"
      },
      {
        "status": "unaffected",
        "version": "4.19.209",
        "versionType": "custom",
        "lessThanOrEqual": "4.19.*"
      },
      {
        "status": "unaffected",
        "version": "5.4.151",
        "versionType": "custom",
        "lessThanOrEqual": "5.4.*"
      },
      {
        "status": "unaffected",
        "version": "5.10.71",
        "versionType": "custom",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.14.10",
        "versionType": "custom",
        "lessThanOrEqual": "5.14.*"
      },
      {
        "status": "unaffected",
        "version": "5.15",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "kernel/sched/cpufreq_schedutil.c"
    ],
    "defaultStatus": "affected"
  }
]