CVE-2025-21899

~# cd /sys/kernel/tracing/events/rcu/rcucallback ~# echo 'hist:name=bad:keys=commonpid:onmax(bogus).save(commonpid)' > trigger bash: echo: write error: Invalid argument ~# echo 'hist:name=bad:keys=commonpid' > trigger

Because the following occurs:

eventtriggerwrite() { triggerprocessregex() { eventhisttrigger_parse() {

  data = event_trigger_alloc(..);

  event_trigger_register(.., data) {
    cmd_ops->reg(.., data, ..) [hist_register_trigger()] {
      data->ops->init() [event_hist_trigger_init()] {
        save_named_trigger(name, data) {
          list_add(&data->named_list, &named_triggers);
        }
      }
    }
  }

  ret = create_actions(); (return -EINVAL)
  if (ret)
    goto out_unreg;

[..] ret = histtriggerenable(data, ...) { listaddtailrcu(&data->list, &file->triggers); <<<---- SKIPPED!!! (this is important!) [..] outunreg: eventhistunregister(.., data) { cmdops->unreg(.., data, ..) [histunregistertrigger()] { listforeachentry(iter, &file->triggers, list) { if (!histtriggermatch(data, iter, named_data, false)) <- never matches continue; [..] test = iter; } if (test && test->ops->free) <<<-- test is NULL

        test->ops->free(test) [event_hist_trigger_free()] {
          [..]
          if (data->name)
            del_named_trigger(data) {
              list_del(&data->named_list);  <<<<-- NEVER gets removed!
            }
          }
       }
     }

     [..]
     kfree(data); <<<-- frees item but it is still on list

The next time a hist with name is registered, it causes an u-a-f bug and the kernel can crash.

Move the code around such that if eventtriggerregister() succeeds, the next thing called is histtriggerenable() which adds it to the list.

A bunch of actions is called if getnamedtriggerdata() returns false. But that doesn't need to be called after eventtriggerregister(), so it can be moved up, allowing eventtriggerregister() to be called just before histtrigger_enable() keeping them together and allowing the file->triggers to be properly populated.

References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type: GIT
Repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events: Introduced

067fe038e70f6e64960d26a79c4df5f1413d0f13

Fixed

5ae1b18f05ee2b849dc03b6c15d7da0c1c6efa77

Type: GIT
Repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events: Introduced

067fe038e70f6e64960d26a79c4df5f1413d0f13

Fixed

43b254d46c740bf9dbe65709afa021dd726dfa99

Type: GIT
Repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events: Introduced

067fe038e70f6e64960d26a79c4df5f1413d0f13

Fixed

435d2964af815aae456db554c62963b4515f19d0

Type: GIT
Repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events: Introduced

067fe038e70f6e64960d26a79c4df5f1413d0f13

Fixed

f1ae50cfb818ce1ac7a674406dfadb7653e2552d

Type: GIT
Repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events: Introduced

067fe038e70f6e64960d26a79c4df5f1413d0f13

Fixed

6f86bdeab633a56d5c6dccf1a2c5989b6a5e323e

Affected versions

v4.*

v4.16

v4.16-rc5

v4.16-rc6

v4.16-rc7

v4.17

v4.17-rc1

v4.17-rc2

v4.17-rc3

v4.17-rc4

v4.17-rc5

v4.17-rc6

v4.17-rc7

v4.18

v4.18-rc1

v4.18-rc2

v4.18-rc3

v4.18-rc4

v4.18-rc5

v4.18-rc6

v4.18-rc7

v4.18-rc8

v4.19

v4.19-rc1

v4.19-rc2

v4.19-rc3

v4.19-rc4

v4.19-rc5

v4.19-rc6

v4.19-rc7

v4.19-rc8

v4.20

v4.20-rc1

v4.20-rc2

v4.20-rc3

v4.20-rc4

v4.20-rc5

v4.20-rc6

v4.20-rc7

v5.*

v5.0

v5.0-rc1

v5.0-rc2

v5.0-rc3

v5.0-rc4

v5.0-rc5

v5.0-rc6

v5.0-rc7

v5.0-rc8

v5.1

v5.1-rc1

v5.1-rc2

v5.1-rc3

v5.1-rc4

v5.1-rc5

v5.1-rc6

v5.1-rc7

v5.10

v5.10-rc1

v5.10-rc2

v5.10-rc3

v5.10-rc4

v5.10-rc5

v5.10-rc6

v5.10-rc7

v5.11

v5.11-rc1

v5.11-rc2

v5.11-rc3

v5.11-rc4

v5.11-rc5

v5.11-rc6

v5.11-rc7

v5.12

v5.12-rc1

v5.12-rc1-dontuse

v5.12-rc2

v5.12-rc3

v5.12-rc4

v5.12-rc5

v5.12-rc6

v5.12-rc7

v5.12-rc8

v5.13

v5.13-rc1

v5.13-rc2

v5.13-rc3

v5.13-rc4

v5.13-rc5

v5.13-rc6

v5.13-rc7

v5.14

v5.14-rc1

v5.14-rc2

v5.14-rc3

v5.14-rc4

v5.14-rc5

v5.14-rc6

v5.14-rc7

v5.15

v5.15-rc1

v5.15-rc2

v5.15-rc3

v5.15-rc4

v5.15-rc5

v5.15-rc6

v5.15-rc7

v5.16

v5.16-rc1

v5.16-rc2

v5.16-rc3

v5.16-rc4

v5.16-rc5

v5.16-rc6

v5.16-rc7

v5.16-rc8

v5.17

v5.17-rc1

v5.17-rc2

v5.17-rc3

v5.17-rc4

v5.17-rc5

v5.17-rc6

v5.17-rc7

v5.17-rc8

v5.18

v5.18-rc1

v5.18-rc2

v5.18-rc3

v5.18-rc4

v5.18-rc5

v5.18-rc6

v5.18-rc7

v5.19

v5.19-rc1

v5.19-rc2

v5.19-rc3

v5.19-rc4

v5.19-rc5

v5.19-rc6

v5.19-rc7

v5.19-rc8

v5.2

v5.2-rc1

v5.2-rc2

v5.2-rc3

v5.2-rc4

v5.2-rc5

v5.2-rc6

v5.2-rc7

v5.3

v5.3-rc1

v5.3-rc2

v5.3-rc3

v5.3-rc4

v5.3-rc5

v5.3-rc6

v5.3-rc7

v5.3-rc8

v5.4

v5.4-rc1

v5.4-rc2

v5.4-rc3

v5.4-rc4

v5.4-rc5

v5.4-rc6

v5.4-rc7

v5.4-rc8

v5.5

v5.5-rc1

v5.5-rc2

v5.5-rc3

v5.5-rc4

v5.5-rc5

v5.5-rc6

v5.5-rc7

v5.6

v5.6-rc1

v5.6-rc2

v5.6-rc3

v5.6-rc4

v5.6-rc5

v5.6-rc6

v5.6-rc7

v5.7

v5.7-rc1

v5.7-rc2

v5.7-rc3

v5.7-rc4

v5.7-rc5

v5.7-rc6

v5.7-rc7

v5.8

v5.8-rc1

v5.8-rc2

v5.8-rc3

v5.8-rc4

v5.8-rc5

v5.8-rc6

v5.8-rc7

v5.9

v5.9-rc1

v5.9-rc2

v5.9-rc3

v5.9-rc4

v5.9-rc5

v5.9-rc6

v5.9-rc7

v5.9-rc8

v6.*

v6.0

v6.0-rc1

v6.0-rc2

v6.0-rc3

v6.0-rc4

v6.0-rc5

v6.0-rc6

v6.0-rc7

v6.1

v6.1-rc1

v6.1-rc2

v6.1-rc3

v6.1-rc4

v6.1-rc5

v6.1-rc6

v6.1-rc7

v6.1-rc8

v6.1.1

v6.1.10

v6.1.100

v6.1.101

v6.1.102

v6.1.103

v6.1.104

v6.1.105

v6.1.106

v6.1.107

v6.1.108

v6.1.109

v6.1.11

v6.1.110

v6.1.111

v6.1.112

v6.1.113

v6.1.114

v6.1.115

v6.1.116

v6.1.117

v6.1.118

v6.1.119

v6.1.12

v6.1.120

v6.1.121

v6.1.122

v6.1.123

v6.1.124

v6.1.125

v6.1.126

v6.1.127

v6.1.128

v6.1.129

v6.1.13

v6.1.14

v6.1.15

v6.1.16

v6.1.17

v6.1.18

v6.1.19

v6.1.2

v6.1.20

v6.1.21

v6.1.22

v6.1.23

v6.1.24

v6.1.25

v6.1.26

v6.1.27

v6.1.28

v6.1.29

v6.1.3

v6.1.30

v6.1.31

v6.1.32

v6.1.33

v6.1.34

v6.1.35

v6.1.36

v6.1.37

v6.1.38

v6.1.39

v6.1.4

v6.1.40

v6.1.41

v6.1.42

v6.1.43

v6.1.44

v6.1.45

v6.1.46

v6.1.47

v6.1.48

v6.1.49

v6.1.5

v6.1.50

v6.1.51

v6.1.52

v6.1.53

v6.1.54

v6.1.55

v6.1.56

v6.1.57

v6.1.58

v6.1.59

v6.1.6

v6.1.60

v6.1.61

v6.1.62

v6.1.63

v6.1.64

v6.1.65

v6.1.66

v6.1.67

v6.1.68

v6.1.69

v6.1.7

v6.1.70

v6.1.71

v6.1.72

v6.1.73

v6.1.74

v6.1.75

v6.1.76

v6.1.77

v6.1.78

v6.1.79

v6.1.8

v6.1.80

v6.1.81

v6.1.82

v6.1.83

v6.1.84

v6.1.85

v6.1.86

v6.1.87

v6.1.88

v6.1.89

v6.1.9

v6.1.90

v6.1.91

v6.1.92

v6.1.93

v6.1.94

v6.1.95

v6.1.96

v6.1.97

v6.1.98

v6.1.99

v6.10

v6.10-rc1

v6.10-rc2

v6.10-rc3

v6.10-rc4

v6.10-rc5

v6.10-rc6

v6.10-rc7

v6.11

v6.11-rc1

v6.11-rc2

v6.11-rc3

v6.11-rc4

v6.11-rc5

v6.11-rc6

v6.11-rc7

v6.12

v6.12-rc1

v6.12-rc2

v6.12-rc3

v6.12-rc4

v6.12-rc5

v6.12-rc6

v6.12-rc7

v6.12.1

v6.12.10

v6.12.11

v6.12.12

v6.12.13

v6.12.14

v6.12.15

v6.12.16

v6.12.17

v6.12.2

v6.12.3

v6.12.4

v6.12.5

v6.12.6

v6.12.7

v6.12.8

v6.12.9

v6.13

v6.13-rc1

v6.13-rc2

v6.13-rc3

v6.13-rc4

v6.13-rc5

v6.13-rc6

v6.13-rc7

v6.13.1

v6.13.2

v6.13.3

v6.13.4

v6.13.5

v6.14-rc1

v6.14-rc2

v6.14-rc3

v6.14-rc4

v6.2

v6.2-rc1

v6.2-rc2

v6.2-rc3

v6.2-rc4

v6.2-rc5

v6.2-rc6

v6.2-rc7

v6.2-rc8

v6.3

v6.3-rc1

v6.3-rc2

v6.3-rc3

v6.3-rc4

v6.3-rc5

v6.3-rc6

v6.3-rc7

v6.4

v6.4-rc1

v6.4-rc2

v6.4-rc3

v6.4-rc4

v6.4-rc5

v6.4-rc6

v6.4-rc7

v6.5

v6.5-rc1

v6.5-rc2

v6.5-rc3

v6.5-rc4

v6.5-rc5

v6.5-rc6

v6.5-rc7

v6.6

v6.6-rc1

v6.6-rc2

v6.6-rc3

v6.6-rc4

v6.6-rc5

v6.6-rc6

v6.6-rc7

v6.6.1

v6.6.10

v6.6.11

v6.6.12

v6.6.13

v6.6.14

v6.6.15

v6.6.16

v6.6.17

v6.6.18

v6.6.19

v6.6.2

v6.6.20

v6.6.21

v6.6.22

v6.6.23

v6.6.24

v6.6.25

v6.6.26

v6.6.27

v6.6.28

v6.6.29

v6.6.3

v6.6.30

v6.6.31

v6.6.32

v6.6.33

v6.6.34

v6.6.35

v6.6.36

v6.6.37

v6.6.38

v6.6.39

v6.6.4

v6.6.40

v6.6.41

v6.6.42

v6.6.43

v6.6.44

v6.6.45

v6.6.46

v6.6.47

v6.6.48

v6.6.49

v6.6.5

v6.6.50

v6.6.51

v6.6.52

v6.6.53

v6.6.54

v6.6.55

v6.6.56

v6.6.57

v6.6.58

v6.6.59

v6.6.6

v6.6.60

v6.6.61

v6.6.62

v6.6.63

v6.6.64

v6.6.65

v6.6.66

v6.6.67

v6.6.68

v6.6.69

v6.6.7

v6.6.70

v6.6.71

v6.6.72

v6.6.73

v6.6.74

v6.6.75

v6.6.76

v6.6.77

v6.6.78

v6.6.79

v6.6.8

v6.6.80

v6.6.9

v6.7

v6.7-rc1

v6.7-rc2

v6.7-rc3

v6.7-rc4

v6.7-rc5

v6.7-rc6

v6.7-rc7

v6.7-rc8

v6.8

v6.8-rc1

v6.8-rc2

v6.8-rc3

v6.8-rc4

v6.8-rc5

v6.8-rc6

v6.8-rc7

v6.9

v6.9-rc1

v6.9-rc2

v6.9-rc3

v6.9-rc4

v6.9-rc5

v6.9-rc6

v6.9-rc7

Linux / Kernel

Package

Name: Kernel

Affected ranges

Type: ECOSYSTEM
Events: Introduced

4.17.0

Fixed

6.1.130

Type: ECOSYSTEM
Events: Introduced

6.2.0

Fixed

6.6.81

Type: ECOSYSTEM
Events: Introduced

6.7.0

Fixed

6.12.18

Type: ECOSYSTEM
Events: Introduced

6.13.0

Fixed

6.13.6