DEBIAN-CVE-2025-21857
Record from OSV · Published March 12, 2025
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]
Fixed versions
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| Package | Ecosystem | Fixed in |
|---|---|---|
| linux | Debian:14 | 6.12.17-1 |
| linux | Debian:13 | 6.12.17-1 |
Risk scores
Affected products
| Vendor | Product | Versions |
|---|---|---|
| Debian:14 | linux | 0 |
| Debian:13 | linux | 0 |
Timeline
- Mar 12, 2025 CVE Published
- Sep 1, 2026 CVE Updated
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