UBUNTU-CVE-2025-40260
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix scx_enable() crash on helper kthread creation failure A crash was observed when the sched_ext selftests runner was terminated with Ctrl+\ while test 15 was running: NIP [c00000000028fa58] scx_enable.constprop.0+0x358/0x12b0 LR [c00000000028fa2c] scx_enable.constprop.0+0x32c/0x12b0 Call Trace: scx_enable.constprop.0+0x32c/0x12b0 (unreliable) bpf_struct_ops_link_create+0x18c/0x22c __sys_bpf+0x23f8/0x3044 sys_bpf+0x2c/0x6c system_call_exception+0x124/0x320 system_call_vectored_common+0x15c/0x2ec kthread_run_worker() returns an ERR_PTR() on failure rather than NULL, but the current code in scx_alloc_and_add_sched() only checks for a NULL helper. Incase of failure on SIGQUIT, the error is not handled in scx_alloc_and_add_sched() and scx_enable() ends up dereferencing an error pointer. Error handling is fixed in scx_alloc_and_add_sched() to propagate PTR_ERR() into ret, so that scx_enable() jumps to the existing error path, avoiding random dereference on failure.
02 / AFFECTED SOFTWARE
Affected packages
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03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix scx_enable() crash on helper kthread creation failure A crash was observed when the sched_ext selftests runner was terminated with Ctrl+\ while test 15 was running: NIP [c00000000028fa58] scx_enable.constprop.0+0x358/0x12b0 LR [c00000000028fa2c] scx_enable.constprop.0+0x32c/0x12b0 Call Trace: scx_enable.constprop.0+0x32c/0x12b0 (unreliable) bpf_struct_ops_link_create+0x18c/0x22c __sys_bpf+0x23f8/0x3044 sys_bpf+0x2c/0x6c system_call_exception+0x124/0x320 system_call_vectored_common+0x15c/0x2ec kthread_run_worker() returns an ERR_PTR() on failure rather than NULL, but the current code in scx_alloc_and_add_sched() only checks for a NULL helper. Incase of failure on SIGQUIT, the error is not handled in scx_alloc_and_add_sched() and scx_enable() ends up dereferencing an error pointer. Error handling is fixed in scx_alloc_and_add_sched() to propagate PTR_ERR() into ret, so that scx_enable() jumps to the existing error path, avoiding random dereference on failure.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/7b6216baae751369195fa3c83d434d23bcda406a
- https://git.kernel.org/stable/c/625e173e2a59b6cf6cbfb51c0a6bea47f3861eab
- https://git.kernel.org/stable/c/7b6216baae751369195fa3c83d434d23bcda406a
- https://ubuntu.com/security/CVE-2025-40260
- https://ubuntu.com/security/notices/USN-8094-1
- https://ubuntu.com/security/notices/USN-8094-2
- https://ubuntu.com/security/notices/USN-8094-3
- https://ubuntu.com/security/notices/USN-8094-4
- https://ubuntu.com/security/notices/USN-8094-5
- https://ubuntu.com/security/notices/USN-8152-1
- https://www.cve.org/CVERecord?id=CVE-2025-40260