CVE-2026-43238net/sched: act_skbedit: fix divide-by-zero in tcf_skbedit_hash()

Official description

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_skbedit: fix divide-by-zero in tcf_skbedit_hash() Commit 38a6f0865796 ("net: sched: support hash selecting tx queue") added SKBEDIT_F_TXQ_SKBHASH support. The inclusive range size is computed as: mapping_mod = queue_mapping_max - queue_mapping + 1; The range size can be 65536 when the requested range covers all possible u16 queue IDs (e.g. queue_mapping=0 and queue_mapping_max=U16_MAX). That value cannot be represented in a u16 and previously wrapped to 0, so tcf_skbedit_hash() could trigger a divide-by-zero: queue_mapping += skb_get_hash(skb) % params->mapping_mod; Compute mapping_mod in a wider type and reject ranges larger than U16_MAX to prevent params->mapping_mod from becoming 0 and avoid the crash.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/59809fda4da7730cfe84a948033f47eb45db073d
• https://git.kernel.org/stable/c/9c735a7d98c982a786b0db71eb6566ee00aaa04f
• https://git.kernel.org/stable/c/015cebdfcb97b5347fb7f598ea712a281cb35840
• https://git.kernel.org/stable/c/4ece5eb4836f8ff03b9004dc2430a7169f282851
• https://git.kernel.org/stable/c/3c2b95b26860bd6f8e2310d31ea1200d3f8f173e
• https://git.kernel.org/stable/c/be054cc66f739a9ba615dba9012a07fab8e7dd6f