CVE-2025-38282

The active reference lifecycle provides the break/unbreak mechanism but the active reference is not truly active after unbreak -- callers don't use it afterwards but it's important for proper pairing of kn->active counting. Assuming this mechanism is in place, the WARN check in kernfsshoulddrainopenfiles() is too sensitive -- it may transiently catch those (rightful) callers between kernfsunbreakactiveprotection() and kernfsput_active() as found out by Chen Ridong:

kernfs_remove_by_name_ns    kernfs_get_active // active=1
__kernfs_remove                   // active=0x80000002
kernfs_drain            ...
wait_event
//waiting (active == 0x80000001)
                kernfs_break_active_protection
                // active = 0x80000001
// continue
                kernfs_unbreak_active_protection
                // active = 0x80000002
...
kernfs_should_drain_open_files
// warning occurs
                kernfs_put_active

To avoid the false positives (mind paniconwarn) remove the check altogether. (This is meant as quick fix, I think active reference break/unbreak may be simplified with larger rework.)

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

bdb2fd7fc56e197a63c0b0e7e07d25d5e20e7c72

Fixed

2d6a67c2b3b87808a347dc1047b520a9dd177a4f

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

bdb2fd7fc56e197a63c0b0e7e07d25d5e20e7c72

Fixed

6c81f1c7812c61f187bed1b938f1d2e391d503ab

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

bdb2fd7fc56e197a63c0b0e7e07d25d5e20e7c72

Fixed

6bfb154f95d5f0ab7ed056f23aba8c1a94cb3927

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

bdb2fd7fc56e197a63c0b0e7e07d25d5e20e7c72

Fixed

72275c888f8962b406ee9c6885c79bf68cca5a63

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

bdb2fd7fc56e197a63c0b0e7e07d25d5e20e7c72

Fixed

071d8e4c2a3b0999a9b822e2eb8854784a350f8a

Affected versions

v6.*

v6.0

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

v6.1.130

v6.1.131

v6.1.132

v6.1.133

v6.1.134

v6.1.135

v6.1.136

v6.1.137

v6.1.138

v6.1.139

v6.1.14

v6.1.140

v6.1.141

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

v6.12.18

v6.12.19

v6.12.2

v6.12.20

v6.12.21

v6.12.22

v6.12.23

v6.12.24

v6.12.25

v6.12.26

v6.12.27

v6.12.28

v6.12.29

v6.12.3

v6.12.30

v6.12.31

v6.12.32

v6.12.33

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

v6.14

v6.14-rc1

v6.14-rc2

v6.14-rc3

v6.14-rc4

v6.14-rc5

v6.14-rc6

v6.14-rc7

v6.15

v6.15-rc1

v6.15-rc2

v6.15-rc3

v6.15-rc4

v6.15-rc5

v6.15-rc6

v6.15-rc7

v6.15.1

v6.15.2

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

v6.6.81

v6.6.82

v6.6.83

v6.6.84

v6.6.85

v6.6.86

v6.6.87

v6.6.88

v6.6.89

v6.6.9

v6.6.90

v6.6.91

v6.6.92

v6.6.93

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

6.1.0

Fixed

6.1.142

Type: ECOSYSTEM
Events: Introduced

6.2.0

Fixed

6.6.94

Type: ECOSYSTEM
Events: Introduced

6.7.0

Fixed

6.12.34

Type: ECOSYSTEM
Events: Introduced

6.13.0

Fixed

6.15.3