CVE-2026-93100

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Source
https://cve.org/CVERecord?id=CVE-2026-93100
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93100.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-93100
Downstream
Published
2026-09-17T16:11:13Z
Modified
2026-09-19T03:47:31Z
Summary
fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()
Details

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

fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()

A struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that need the structure to remain valid across a sleep (while waiting on acquiring rdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with rdtgroup_kn_put().

The release path is intended to serve as the fallback freer: if the count drops to zero and the group has already been marked RDT_DELETED, rdtgroup_kn_put() frees the structure.

The bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting from a resctrl directory remove or resctrl fs unmount act as the primary freer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is zero, otherwise they set RDT_DELETED and leave the freeing to the last waiter.

These two freers race. rdtgroup_kn_put() commits waitcount == 0 with atomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags. Between those two operations a concurrent caller of free_all_child_rdtgrp() or rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via atomic_read(), call rdtgroup_remove(), and kfree() the structure.

The subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then a use-after-free, and the structure may even be freed twice if the freed memory happens to satisfy the RDT_DELETED flag check.

Replace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so that the decrement-to-zero takes rdtgroup_mutex before the count becomes globally visible. The inspection of rdtgroup::flags then runs under the same mutex held by the bulk freers, making the two paths mutually exclusive.

The common case where the count does not reach zero remains lock-free. Defer kernfs_unbreak_active_protection() until after the mutex is dropped since kernfs active protections functionally wrap rdtgroup_mutex. Remove resource group, which in turn drops its kernfs reference, after kernfs protection is restored.

[ bp: Split the commit messsages into smaller, easier-parseable paragraphs. ]

Database specific 
{
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93100.json"
}
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
b8511ccc75c033f6d54188ea4df7bf1e85778740
Fixed
ae69f936e8ffed553d899ba4c02f8a7461a89e54
Fixed
4c593c62c1499665baebbb41b70e2c9b7e947b86
Fixed
f5bcf539484d2d604c2f2330e09487ea090b21c7
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Last Affected
d20edc0bca5577bab38acb5b190619c922ddebf8
Last Affected
1b006f8cbde9f3dabdfafe2ff7aa9f831ed5b625
Last Affected
40300f986e47dbc8f1d02e5080385f5cf9f85f70
Last Affected
b5a4949897ebada8132d54c93208989482503103
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
4.14.170
Fixed
4.15
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
4.19.102
Fixed
4.20
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
5.4.18
Fixed
5.5
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
5.5.2
Fixed
5.6

Affected versions

v2.*
v2.6.12-rc2
v2.6.12-rc3
v2.6.12-rc4
v2.6.13
v2.6.13-rc1
v2.6.13-rc2
v2.6.13-rc3
v2.6.13-rc4
v2.6.13-rc5
v2.6.13-rc6
v2.6.13-rc7
v2.6.14-rc1
v2.6.14-rc2
v2.6.14-rc3
v2.6.15-rc1
v2.6.15-rc2
v2.6.15-rc4
v2.6.15-rc5
v2.6.15-rc7
v2.6.16
v2.6.16-rc1
v2.6.16-rc2
v2.6.16-rc3
v2.6.16-rc4
v2.6.16-rc5
v2.6.16-rc6
v2.6.17
v2.6.17-rc1
v2.6.17-rc2
v2.6.17-rc3
v2.6.17-rc4
v2.6.17-rc5
v2.6.17-rc6
v2.6.18
v2.6.18-rc1
v2.6.18-rc2
v2.6.18-rc3
v2.6.18-rc5
v2.6.18-rc6
v2.6.19-rc1
v2.6.19-rc2
v2.6.20-rc1
v2.6.20-rc2
v2.6.20-rc3
v2.6.20-rc4
v2.6.20-rc5
v2.6.20-rc6
v2.6.20-rc7
v2.6.21
v2.6.21-rc1
v2.6.21-rc2
v2.6.21-rc3
v2.6.21-rc4
v2.6.21-rc5
v2.6.21-rc6
v2.6.21-rc7
v2.6.22
v2.6.22-rc1
v2.6.22-rc2
v2.6.22-rc3
v2.6.22-rc4
v2.6.22-rc5
v2.6.22-rc6
v2.6.22-rc7
v2.6.23
v2.6.23-rc1
v2.6.23-rc2
v2.6.23-rc3
v2.6.23-rc4
v2.6.23-rc5
v2.6.23-rc6
v2.6.23-rc7
v2.6.23-rc8
v2.6.23-rc9
v2.6.24
v2.6.24-rc1
v2.6.24-rc2
v2.6.24-rc3
v2.6.24-rc4
v2.6.24-rc5
v2.6.24-rc6
v2.6.24-rc7
v2.6.24-rc8
v2.6.25
v2.6.25-rc1
v2.6.25-rc2
v2.6.25-rc3
v2.6.25-rc4
v2.6.25-rc5
v2.6.25-rc6
v2.6.25-rc7
v2.6.25-rc8
v2.6.25-rc9
v2.6.26
v2.6.26-rc1
v2.6.26-rc2
v2.6.26-rc3
v2.6.26-rc4
v2.6.26-rc5
v2.6.26-rc6
v2.6.26-rc7
v2.6.26-rc8
v2.6.26-rc9
v2.6.27
v2.6.27-rc1
v2.6.27-rc2
v2.6.27-rc3
v2.6.27-rc4
v2.6.27-rc5
v2.6.27-rc6
v2.6.27-rc7
v2.6.27-rc8
v2.6.27-rc9
v2.6.28
v2.6.28-rc1
v2.6.28-rc2
v2.6.28-rc3
v2.6.28-rc4
v2.6.28-rc5
v2.6.28-rc6
v2.6.28-rc7
v2.6.28-rc8
v2.6.28-rc9
v2.6.29
v2.6.29-rc1
v2.6.29-rc2
v2.6.29-rc3
v2.6.29-rc4
v2.6.29-rc5
v2.6.29-rc6
v2.6.29-rc7
v2.6.29-rc8
v2.6.30
v2.6.30-rc1
v2.6.30-rc2
v2.6.30-rc3
v2.6.30-rc4
v2.6.30-rc5
v2.6.30-rc6
v2.6.30-rc7
v2.6.30-rc8
v2.6.31
v2.6.31-rc1
v2.6.31-rc2
v2.6.31-rc3
v2.6.31-rc4
v2.6.31-rc5
v2.6.31-rc6
v2.6.31-rc7
v2.6.31-rc8
v2.6.31-rc9
v2.6.32
v2.6.32-rc1
v2.6.32-rc2
v2.6.32-rc3
v2.6.32-rc4
v2.6.32-rc5
v2.6.32-rc6
v2.6.32-rc7
v2.6.32-rc8
v2.6.33
v2.6.33-rc1
v2.6.33-rc2
v2.6.33-rc3
v2.6.33-rc4
v2.6.33-rc5
v2.6.33-rc6
v2.6.33-rc7
v2.6.33-rc8
v2.6.34
v2.6.34-rc1
v2.6.34-rc2
v2.6.34-rc3
v2.6.34-rc4
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v2.6.35
v2.6.35-rc1
v2.6.35-rc2
v2.6.35-rc3
v2.6.35-rc4
v2.6.35-rc5
v2.6.35-rc6
v2.6.36
v2.6.36-rc1
v2.6.36-rc2
v2.6.36-rc3
v2.6.36-rc4
v2.6.36-rc5
v2.6.36-rc6
v2.6.36-rc7
v2.6.36-rc8
v2.6.37
v2.6.37-rc1
v2.6.37-rc2
v2.6.37-rc3
v2.6.37-rc4
v2.6.37-rc5
v2.6.37-rc6
v2.6.37-rc7
v2.6.37-rc8
v2.6.38
v2.6.38-rc1
v2.6.38-rc2
v2.6.38-rc3
v2.6.38-rc4
v2.6.38-rc5
v2.6.38-rc6
v2.6.38-rc7
v2.6.38-rc8
v2.6.39
v2.6.39-rc1
v2.6.39-rc2
v2.6.39-rc3
v2.6.39-rc4
v2.6.39-rc5
v2.6.39-rc6
v2.6.39-rc7
v3.*
v3.0
v3.0-rc1
v3.0-rc2
v3.0-rc3
v3.0-rc4
v3.0-rc5
v3.0-rc6
v3.0-rc7
v3.1
v3.1-rc1
v3.1-rc10
v3.1-rc2
v3.1-rc3
v3.1-rc4
v3.1-rc5
v3.1-rc6
v3.1-rc7
v3.1-rc8
v3.1-rc9
v3.10
v3.10-rc1
v3.10-rc2
v3.10-rc3
v3.10-rc4
v3.10-rc5
v3.10-rc6
v3.10-rc7
v3.11
v3.11-rc1
v3.11-rc2
v3.11-rc3
v3.11-rc4
v3.11-rc5
v3.11-rc6
v3.11-rc7
v3.12
v3.12-rc1
v3.12-rc2
v3.12-rc3
v3.12-rc4
v3.12-rc5
v3.12-rc6
v3.12-rc7
v3.13
v3.13-rc1
v3.13-rc2
v3.13-rc3
v3.13-rc4
v3.13-rc5
v3.13-rc6
v3.13-rc7
v3.13-rc8
v3.14
v3.14-rc1
v3.14-rc2
v3.14-rc3
v3.14-rc4
v3.14-rc5
v3.14-rc6
v3.14-rc7
v3.14-rc8
v3.15
v3.15-rc1
v3.15-rc2
v3.15-rc3
v3.15-rc4
v3.15-rc5
v3.15-rc6
v3.15-rc7
v3.15-rc8
v3.16
v3.16-rc1
v3.16-rc2
v3.16-rc3
v3.16-rc4
v3.16-rc5
v3.16-rc6
v3.16-rc7
v3.17
v3.17-rc1
v3.17-rc2
v3.17-rc3
v3.17-rc4
v3.17-rc5
v3.17-rc6
v3.17-rc7
v3.18
v3.18-rc1
v3.18-rc2
v3.18-rc3
v3.18-rc4
v3.18-rc5
v3.18-rc6
v3.18-rc7
v3.19
v3.19-rc1
v3.19-rc2
v3.19-rc3
v3.19-rc4
v3.19-rc5
v3.19-rc6
v3.19-rc7
v3.2
v3.2-rc1
v3.2-rc2
v3.2-rc3
v3.2-rc4
v3.2-rc5
v3.2-rc6
v3.2-rc7
v3.3
v3.3-rc1
v3.3-rc2
v3.3-rc3
v3.3-rc4
v3.3-rc5
v3.3-rc6
v3.3-rc7
v3.4
v3.4-rc1
v3.4-rc2
v3.4-rc3
v3.4-rc4
v3.4-rc5
v3.4-rc6
v3.4-rc7
v3.5
v3.5-rc1
v3.5-rc2
v3.5-rc3
v3.5-rc4
v3.5-rc5
v3.5-rc6
v3.5-rc7
v3.6
v3.6-rc1
v3.6-rc2
v3.6-rc3
v3.6-rc4
v3.6-rc5
v3.6-rc6
v3.6-rc7
v3.7
v3.7-rc1
v3.7-rc2
v3.7-rc3
v3.7-rc4
v3.7-rc5
v3.7-rc6
v3.7-rc7
v3.7-rc8
v3.8
v3.8-rc1
v3.8-rc2
v3.8-rc3
v3.8-rc4
v3.8-rc5
v3.8-rc6
v3.8-rc7
v3.9
v3.9-rc1
v3.9-rc2
v3.9-rc3
v3.9-rc4
v3.9-rc5
v3.9-rc6
v3.9-rc7
v3.9-rc8
v4.*
v4.0
v4.0-rc1
v4.0-rc2
v4.0-rc3
v4.0-rc4
v4.0-rc5
v4.0-rc6
v4.0-rc7
v4.1
v4.1-rc1
v4.1-rc2
v4.1-rc3
v4.1-rc4
v4.1-rc5
v4.1-rc6
v4.1-rc7
v4.1-rc8
v4.10
v4.10-rc1
v4.10-rc2
v4.10-rc3
v4.10-rc4
v4.10-rc5
v4.10-rc6
v4.10-rc7
v4.10-rc8
v4.11
v4.11-rc1
v4.11-rc2
v4.11-rc3
v4.11-rc4
v4.11-rc5
v4.11-rc6
v4.11-rc7
v4.11-rc8
v4.12
v4.12-rc1
v4.12-rc2
v4.12-rc3
v4.12-rc4
v4.12-rc5
v4.12-rc6
v4.12-rc7
v4.13
v4.13-rc1
v4.13-rc2
v4.13-rc3
v4.13-rc4
v4.13-rc5
v4.13-rc6
v4.13-rc7
v4.14
v4.14-rc1
v4.14-rc2
v4.14-rc3
v4.14-rc4
v4.14-rc5
v4.14-rc6
v4.14-rc7
v4.14-rc8
v4.14.1
v4.14.10
v4.14.100
v4.14.101
v4.14.102
v4.14.103
v4.14.104
v4.14.105
v4.14.106
v4.14.107
v4.14.108
v4.14.109
v4.14.11
v4.14.110
v4.14.111
v4.14.112
v4.14.113
v4.14.114
v4.14.115
v4.14.116
v4.14.117
v4.14.118
v4.14.119
v4.14.12
v4.14.120
v4.14.121
v4.14.122
v4.14.123
v4.14.124
v4.14.125
v4.14.126
v4.14.127
v4.14.128
v4.14.129
v4.14.13
v4.14.130
v4.14.131
v4.14.132
v4.14.133
v4.14.134
v4.14.135
v4.14.136
v4.14.137
v4.14.138
v4.14.139
v4.14.14
v4.14.140
v4.14.141
v4.14.142
v4.14.143
v4.14.144
v4.14.145
v4.14.146
v4.14.147
v4.14.148
v4.14.149
v4.14.15
v4.14.150
v4.14.151
v4.14.152
v4.14.153
v4.14.154
v4.14.155
v4.14.156
v4.14.157
v4.14.158
v4.14.159
v4.14.16
v4.14.160
v4.14.161
v4.14.162
v4.14.163
v4.14.164
v4.14.165
v4.14.166
v4.14.167
v4.14.168
v4.14.169
v4.14.17
v4.14.18
v4.14.19
v4.14.2
v4.14.20
v4.14.21
v4.14.22
v4.14.23
v4.14.24
v4.14.25
v4.14.26
v4.14.27
v4.14.28
v4.14.29
v4.14.3
v4.14.30
v4.14.31
v4.14.32
v4.14.33
v4.14.34
v4.14.35
v4.14.36
v4.14.37
v4.14.38
v4.14.39
v4.14.4
v4.14.40
v4.14.41
v4.14.42
v4.14.43
v4.14.44
v4.14.45
v4.14.46
v4.14.47
v4.14.48
v4.14.49
v4.14.5
v4.14.50
v4.14.51
v4.14.52
v4.14.53
v4.14.54
v4.14.55
v4.14.56
v4.14.57
v4.14.58
v4.14.59
v4.14.6
v4.14.60
v4.14.61
v4.14.62
v4.14.63
v4.14.64
v4.14.65
v4.14.66
v4.14.67
v4.14.68
v4.14.69
v4.14.7
v4.14.70
v4.14.71
v4.14.72
v4.14.73
v4.14.74
v4.14.75
v4.14.76
v4.14.77
v4.14.78
v4.14.79
v4.14.8
v4.14.80
v4.14.81
v4.14.82
v4.14.83
v4.14.84
v4.14.85
v4.14.86
v4.14.87
v4.14.88
v4.14.89
v4.14.9
v4.14.90
v4.14.91
v4.14.92
v4.14.93
v4.14.94
v4.14.95
v4.14.96
v4.14.97
v4.14.98
v4.14.99
v4.15
v4.15-rc1
v4.15-rc2
v4.15-rc3
v4.15-rc4
v4.15-rc5
v4.15-rc6
v4.15-rc7
v4.15-rc8
v4.15-rc9
v4.16
v4.16-rc1
v4.16-rc2
v4.16-rc3
v4.16-rc4
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
v4.19.1
v4.19.10
v4.19.100
v4.19.101
v4.19.11
v4.19.12
v4.19.13
v4.19.14
v4.19.15
v4.19.16
v4.19.17
v4.19.18
v4.19.19
v4.19.2
v4.19.20
v4.19.21
v4.19.22
v4.19.23
v4.19.24
v4.19.25
v4.19.26
v4.19.27
v4.19.28
v4.19.29
v4.19.3
v4.19.30
v4.19.31
v4.19.32
v4.19.33
v4.19.34
v4.19.35
v4.19.36
v4.19.37
v4.19.38
v4.19.39
v4.19.4
v4.19.40
v4.19.41
v4.19.42
v4.19.43
v4.19.44
v4.19.45
v4.19.46
v4.19.47
v4.19.48
v4.19.49
v4.19.5
v4.19.50
v4.19.51
v4.19.52
v4.19.53
v4.19.54
v4.19.55
v4.19.56
v4.19.57
v4.19.58
v4.19.59
v4.19.6
v4.19.60
v4.19.61
v4.19.62
v4.19.63
v4.19.64
v4.19.65
v4.19.66
v4.19.67
v4.19.68
v4.19.69
v4.19.7
v4.19.70
v4.19.71
v4.19.72
v4.19.73
v4.19.74
v4.19.75
v4.19.76
v4.19.77
v4.19.78
v4.19.79
v4.19.8
v4.19.80
v4.19.81
v4.19.82
v4.19.83
v4.19.84
v4.19.85
v4.19.86
v4.19.87
v4.19.88
v4.19.89
v4.19.9
v4.19.90
v4.19.91
v4.19.92
v4.19.93
v4.19.94
v4.19.95
v4.19.96
v4.19.97
v4.19.98
v4.19.99
v4.2
v4.2-rc1
v4.2-rc2
v4.2-rc3
v4.2-rc4
v4.2-rc5
v4.2-rc6
v4.2-rc7
v4.2-rc8
v4.20
v4.20-rc1
v4.20-rc2
v4.20-rc3
v4.20-rc4
v4.20-rc5
v4.20-rc6
v4.20-rc7
v4.3
v4.3-rc1
v4.3-rc2
v4.3-rc3
v4.3-rc4
v4.3-rc5
v4.3-rc6
v4.3-rc7
v4.4
v4.4-rc1
v4.4-rc2
v4.4-rc3
v4.4-rc4
v4.4-rc5
v4.4-rc6
v4.4-rc7
v4.4-rc8
v4.5
v4.5-rc1
v4.5-rc2
v4.5-rc3
v4.5-rc4
v4.5-rc5
v4.5-rc6
v4.5-rc7
v4.6
v4.6-rc1
v4.6-rc2
v4.6-rc3
v4.6-rc4
v4.6-rc5
v4.6-rc6
v4.6-rc7
v4.7
v4.7-rc1
v4.7-rc2
v4.7-rc3
v4.7-rc4
v4.7-rc5
v4.7-rc6
v4.7-rc7
v4.8
v4.8-rc1
v4.8-rc2
v4.8-rc3
v4.8-rc4
v4.8-rc5
v4.8-rc6
v4.8-rc7
v4.8-rc8
v4.9
v4.9-rc1
v4.9-rc2
v4.9-rc3
v4.9-rc4
v4.9-rc5
v4.9-rc6
v4.9-rc7
v4.9-rc8
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
v5.2
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
v5.4.1
v5.4.10
v5.4.11
v5.4.12
v5.4.13
v5.4.14
v5.4.15
v5.4.16
v5.4.17
v5.4.2
v5.4.3
v5.4.4
v5.4.5
v5.4.6
v5.4.7
v5.4.8
v5.4.9
v5.5
v5.5-rc1
v5.5-rc2
v5.5-rc3
v5.5-rc4
v5.5-rc5
v5.5-rc6
v5.5-rc7
v5.5.1

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93100.json"

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
5.6.0
Fixed
6.18.52
Type
ECOSYSTEM
Events
Introduced
6.19.0
Fixed
7.2.6

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93100.json"