CVE-2025-21857

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_api: fix error handling causing NULL dereference tcf_exts_miss_cookie_base_alloc() calls xa_alloc_cyclic() which can return 1 if the allocation succeeded after wrapping. This was treated as an error, with value 1 returned to caller tcf_exts_init_ex() which sets exts->actions to NULL and returns 1 to caller fl_change(). fl_change() treats err == 1 as success, calling tcf_exts_validate_ex() which calls tcf_action_init() with exts->actions as argument, where it is dereferenced. Example trace: BUG: kernel NULL pointer dereference, address: 0000000000000000 CPU: 114 PID: 16151 Comm: handler114 Kdump: loaded Not tainted 5.14.0-503.16.1.el9_5.x86_64 #1 RIP: 0010:tcf_action_init+0x1f8/0x2c0 Call Trace: tcf_action_init+0x1f8/0x2c0 tcf_exts_validate_ex+0x175/0x190 fl_change+0x537/0x1120 [cls_flower]

CVSS v3 5.5 MEDIUM

5.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.8 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://git.kernel.org/stable/c/071ed42cff4fcdd89025d966d48eabef59913bf2	Patch
https://git.kernel.org/stable/c/3c74b5787caf59bb1e9c5fe0a360643a71eb1e8a	Patch
https://git.kernel.org/stable/c/3e4c56cf41876ef2a82f0877fe2a67648f8632b8	Patch
https://git.kernel.org/stable/c/de4b679aa3b4da7ec34f639df068b914f20e3c3c	Patch

Configurations

Configuration 1 (hide)

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel:6.14:rc1::::::
	cpe:2.3:o:linux:linux_kernel:6.14:rc2::::::
	cpe:2.3:o:linux:linux_kernel:6.14:rc3::::::

History

No history.

Information

Published : 2025-03-12 10:15

Updated : 2025-10-01 20:18

NVD link : CVE-2025-21857

Mitre link : CVE-2025-21857

CVE.ORG link : CVE-2025-21857

JSON object : View

Products Affected

linux

linux_kernel

CWE

CWE-476

NULL Pointer Dereference

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This was treated as\nan error, with value 1 returned to caller tcf_exts_init_ex() which sets\nexts->actions to NULL and returns 1 to caller fl_change().\n\nfl_change() treats err == 1 as success, calling tcf_exts_validate_ex()\nwhich calls tcf_action_init() with exts->actions as argument, where it\nis dereferenced.\n\nExample trace:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nCPU: 114 PID: 16151 Comm: handler114 Kdump: loaded Not tainted 5.14.0-503.16.1.el9_5.x86_64 #1\nRIP: 0010:tcf_action_init+0x1f8/0x2c0\nCall Trace:\n tcf_action_init+0x1f8/0x2c0\n tcf_exts_validate_ex+0x175/0x190\n fl_change+0x537/0x1120 [cls_flower]"}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net/sched: cls_api: se corrige el error de gesti\u00f3n que causa la desreferencia de NULL. tcf_exts_miss_cookie_base_alloc() llama a xa_alloc_cyclic(), que puede devolver 1 si la asignaci\u00f3n se realiz\u00f3 correctamente tras el encapsulado. Esto se trat\u00f3 como un error, con el valor 1 devuelto al llamador tcf_exts_init_ex(), que establece exts->actions en NULL y devuelve 1 al llamador fl_change(). fl_change() trata err == 1 como correcto, llamando a tcf_exts_validate_ex(), que llama a tcf_action_init() con exts->actions como argumento, donde se desreferencia. Ejemplo de seguimiento: ERROR: desreferencia de puntero NULL del n\u00facleo, direcci\u00f3n: 0000000000000000 CPU: 114 PID: 16151 Comm: handler114 Kdump: cargado No contaminado 5.14.0-503.16.1.el9_5.x86_64 #1 RIP: 0010:tcf_action_init+0x1f8/0x2c0 Seguimiento de llamadas: tcf_action_init+0x1f8/0x2c0 tcf_exts_validate_ex+0x175/0x190 fl_change+0x537/0x1120 [cls_flower]"}], "lastModified": "2025-10-01T20:18:29.960", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "ACF3631C-19E5-4953-B4A3-AB7CD48E6A57", "versionEndExcluding": "6.6.80", "versionStartIncluding": "6.3"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "15370AEE-6D1C-49C3-8CB7-E889D5F92B6F", "versionEndExcluding": "6.12.17", "versionStartIncluding": "6.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "72E69ABB-9015-43A6-87E1-5150383CFFD9", "versionEndExcluding": "6.13.5", "versionStartIncluding": "6.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "186716B6-2B66-4BD0-852E-D48E71C0C85F"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "0D3E781C-403A-498F-9DA9-ECEE50F41E75"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "66619FB8-0AAF-4166-B2CF-67B24143261D"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}