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]
                
            Metrics
Affected Vendors & Products
References
        History
                    Wed, 01 Oct 2025 20:15:00 +0000
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| Metrics | ssvc 
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Sat, 12 Jul 2025 13:45:00 +0000
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| Metrics | epss 
 | epss 
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Fri, 14 Mar 2025 02:30:00 +0000
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| References |  | |
| Metrics | threat_severity 
 | threat_severity 
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Thu, 13 Mar 2025 21:45:00 +0000
| Type | Values Removed | Values Added | 
|---|---|---|
| First Time appeared | Linux Linux linux Kernel | |
| Weaknesses | CWE-476 | |
| CPEs | 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:*:*:*:*:*:* | |
| Vendors & Products | Linux Linux linux Kernel | |
| Metrics | cvssV3_1 
 | 
Wed, 12 Mar 2025 09:45:00 +0000
| Type | Values Removed | Values Added | 
|---|---|---|
| Description | 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] | |
| Title | net/sched: cls_api: fix error handling causing NULL dereference | |
| References |  | 
 MITRE
                        MITRE
                    Status: PUBLISHED
Assigner: Linux
Published: 2025-03-12T09:42:10.622Z
Updated: 2025-10-01T19:26:38.155Z
Reserved: 2024-12-29T08:45:45.780Z
Link: CVE-2025-21857
 Vulnrichment
                        Vulnrichment
                    Updated: 2025-10-01T16:58:27.993Z
 NVD
                        NVD
                    Status : Modified
Published: 2025-03-12T10:15:18.583
Modified: 2025-10-01T20:18:29.960
Link: CVE-2025-21857
 Redhat
                        Redhat