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CVE-2026-74740

net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain tcf_action_exec() handles TC_ACT_GOTO_CHAIN by first checking rcu_access_pointer(a->goto_chain) and then calling tcf_action_goto_chain_exec(), which does a second, independent rcu_dereference_bh(a->goto_chain) read and immediately dereferences chain->filter_chain. A concurrent tcf_action_set_ctrlact() (e.g. the gact replace path) can clear a->goto_chain between the two reads, so the second read returns NULL and tcf_action_goto_chain_exec() dereferences NULL. Fix the race by doing a single rcu_dereference_bh() read of a->goto_chain in tcf_action_exec(), checking it once for NULL, and passing the resulting chain pointer into tcf_action_goto_chain_exec(). This turns the split check/use into a single check/use on one value.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 before 91d55fd1fdb85c8371ca8793c788ea7d5192383a; affected ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 before 1ec48b6715c29b20105e3485206602cff6c51ae5; affected ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 before abceabc4408fca6a9dd52611f5d197dec9390d63; affected ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 before 6b70886ebc428eed43a069c8944a931b5fb3f4e4; affected ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 before f60b396ee174206fe08ebf997d16cd3801b77b22
Linux / Linuxaffected 5.1; unaffected 0 before 5.1; unaffected 6.6.153 through 6.6.*; unaffected 6.12.105 through 6.12.*; unaffected 6.18.46 through 6.18.*; unaffected 7.1.10 through 7.1.*; unaffected 7.2 through *

CWE

No CWE identifiers supplied.

References