In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_fw: fix NULL pointer dereference on shared blocks The old-method path in fw_classify() calls tcf_block_q() and dereferences q->handle. Shared blocks leave block->q NULL, causing a NULL deref when an empty cls_fw filter is attached to a shared block and a packet with a nonzero major skb mark is classified. Reject the configuration in fw_change() when the old method (no TCA_OPTIONS) is used on a shared block, since fw_classify()'s old-method path needs block->q which is NULL for shared blocks. The fixed null-ptr-deref calling stack: KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f] RIP: 0010:fw_classify (net/sched/cls_fw.c:81) Call Trace: tcf_classify (./include/net/tc_wrapper.h:197 net/sched/cls_api.c:1764 net/sched/cls_api.c:1860) tc_run (net/core/dev.c:4401) __dev_queue_xmit (net/core/dev.c:4535 net/core/dev.c:4790)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
| Attack Vector | LOCAL |
|---|---|
| Attack Complexity | LOW |
| Privileges Required | LOW |
| User Interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality Impact | NONE |
| Integrity Impact | NONE |
| Availability Impact | HIGH |
| Source | Type | Description |
|---|---|---|
| [email protected] | Primary |
en
CWE-476
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x702b829a7bc0> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bde784c00> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bde784f40> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bde786e00> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702b829a5a00> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702b829a5400> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702b4bc5d3c0> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bde7870c0> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdd6a6b80> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702b829a4a00> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdc372f00> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bcc4086c0> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bddf49dc0> | Operating System |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:* |