CVE-2025-21857
- Source
- https://nvd.nist.gov/vuln/detail/CVE-2025-21857
- Import Source
- https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-21857.json
- JSON Data
- https://api.test.osv.dev/v1/vulns/CVE-2025-21857
- Downstream
- Related
- Published
- 2025-03-12T09:42:10Z
- Modified
- 2025-10-17T22:53:07.088122Z
- Severity
-
- 5.5 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
- Summary
- net/sched: cls_api: fix error handling causing NULL dereference
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
net/sched: cls_api: fix error handling causing NULL dereference
tcfextsmisscookiebasealloc() calls xaalloccyclic() which can return 1 if the allocation succeeded after wrapping. This was treated as an error, with value 1 returned to caller tcfextsinitex() which sets exts->actions to NULL and returns 1 to caller fl_change().
flchange() treats err == 1 as success, calling tcfextsvalidateex() which calls tcfactioninit() 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.el95.x8664 #1 RIP: 0010:tcfactioninit+0x1f8/0x2c0 Call Trace: tcfactioninit+0x1f8/0x2c0 tcfextsvalidateex+0x175/0x190 flchange+0x537/0x1120 [cls_flower]
- References
-
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- https://git.kernel.org/stable/c/071ed42cff4fcdd89025d966d48eabef59913bf2
- https://git.kernel.org/stable/c/3c74b5787caf59bb1e9c5fe0a360643a71eb1e8a
- https://git.kernel.org/stable/c/3e4c56cf41876ef2a82f0877fe2a67648f8632b8
- https://git.kernel.org/stable/c/de4b679aa3b4da7ec34f639df068b914f20e3c3c
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
-
Introduced80cd22c35c9001fe72bf614d29439de41933decaFixedde4b679aa3b4da7ec34f639df068b914f20e3c3c
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced80cd22c35c9001fe72bf614d29439de41933decaFixed3e4c56cf41876ef2a82f0877fe2a67648f8632b8
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced80cd22c35c9001fe72bf614d29439de41933decaFixed3c74b5787caf59bb1e9c5fe0a360643a71eb1e8a
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced80cd22c35c9001fe72bf614d29439de41933decaFixed071ed42cff4fcdd89025d966d48eabef59913bf2