Metrics
Affected Vendors & Products
Wed, 23 Oct 2024 17:15:00 +0000
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Linux
Linux linux Kernel |
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Weaknesses | NVD-CWE-noinfo | |
CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
Vendors & Products |
Linux
Linux linux Kernel |
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Metrics |
cvssV3_1
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cvssV3_1
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Tue, 22 Oct 2024 01:30:00 +0000
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References |
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Metrics |
threat_severity
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cvssV3_1
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Mon, 21 Oct 2024 13:15:00 +0000
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Metrics |
ssvc
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Mon, 21 Oct 2024 12:30:00 +0000
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Description | In the Linux kernel, the following vulnerability has been resolved: bpf: Fix helper writes to read-only maps Lonial found an issue that despite user- and BPF-side frozen BPF map (like in case of .rodata), it was still possible to write into it from a BPF program side through specific helpers having ARG_PTR_TO_{LONG,INT} as arguments. In check_func_arg() when the argument is as mentioned, the meta->raw_mode is never set. Later, check_helper_mem_access(), under the case of PTR_TO_MAP_VALUE as register base type, it assumes BPF_READ for the subsequent call to check_map_access_type() and given the BPF map is read-only it succeeds. The helpers really need to be annotated as ARG_PTR_TO_{LONG,INT} | MEM_UNINIT when results are written into them as opposed to read out of them. The latter indicates that it's okay to pass a pointer to uninitialized memory as the memory is written to anyway. However, ARG_PTR_TO_{LONG,INT} is a special case of ARG_PTR_TO_FIXED_SIZE_MEM just with additional alignment requirement. So it is better to just get rid of the ARG_PTR_TO_{LONG,INT} special cases altogether and reuse the fixed size memory types. For this, add MEM_ALIGNED to additionally ensure alignment given these helpers write directly into the args via *<ptr> = val. The .arg*_size has been initialized reflecting the actual sizeof(*<ptr>). MEM_ALIGNED can only be used in combination with MEM_FIXED_SIZE annotated argument types, since in !MEM_FIXED_SIZE cases the verifier does not know the buffer size a priori and therefore cannot blindly write *<ptr> = val. | |
Title | bpf: Fix helper writes to read-only maps | |
References |
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Status: PUBLISHED
Assigner: Linux
Published: 2024-10-21T12:27:19.321Z
Updated: 2024-11-05T09:50:16.284Z
Reserved: 2024-10-21T12:17:06.017Z
Link: CVE-2024-49861
Updated: 2024-10-21T12:55:42.524Z
Status : Analyzed
Published: 2024-10-21T13:15:06.800
Modified: 2024-10-23T16:48:47.573
Link: CVE-2024-49861