Bug 2324882 (CVE-2024-50253)

Summary: CVE-2024-50253 kernel: bpf: Check the validity of nr_words in bpf_iter_bits_new()
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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Bug Depends On: 2325103    
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Description OSIDB Bzimport 2024-11-09 11:03:06 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bpf: Check the validity of nr_words in bpf_iter_bits_new()

Check the validity of nr_words in bpf_iter_bits_new(). Without this
check, when multiplication overflow occurs for nr_bits (e.g., when
nr_words = 0x0400-0001, nr_bits becomes 64), stack corruption may occur
due to bpf_probe_read_kernel_common(..., nr_bytes = 0x2000-0008).

Fix it by limiting the maximum value of nr_words to 511. The value is
derived from the current implementation of BPF memory allocator. To
ensure compatibility if the BPF memory allocator's size limitation
changes in the future, use the helper bpf_mem_alloc_check_size() to
check whether nr_bytes is too larger. And return -E2BIG instead of
-ENOMEM for oversized nr_bytes.
Comment 1 Avinash Hanwate 2024-11-11 05:57:19 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024110937-CVE-2024-50253-7a6b@gregkh/T