Bug 2335896 (CVE-2024-56768)

Summary: CVE-2024-56768 kernel: bpf: Fix bpf_get_smp_processor_id() on !CONFIG_SMP
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2025-01-06 17:01:40 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix bpf_get_smp_processor_id() on !CONFIG_SMP

On x86-64 calling bpf_get_smp_processor_id() in a kernel with CONFIG_SMP
disabled can trigger the following bug, as pcpu_hot is unavailable:

 [    8.471774] BUG: unable to handle page fault for address: 00000000936a290c
 [    8.471849] #PF: supervisor read access in kernel mode
 [    8.471881] #PF: error_code(0x0000) - not-present page

Fix by inlining a return 0 in the !CONFIG_SMP case.
Comment 1 Robb Gatica 2025-01-06 18:31:27 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025010657-CVE-2024-56768-c835@gregkh/T