CVE - CVE-2024-49861

CVE-ID
CVE-2024-49861	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
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.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/1e75d25133158b525e0456876e9bcfd6b2993fd5 URL:https://git.kernel.org/stable/c/1e75d25133158b525e0456876e9bcfd6b2993fd5 MISC:https://git.kernel.org/stable/c/2ed98ee02d1e08afee88f54baec39ea78dc8a23c URL:https://git.kernel.org/stable/c/2ed98ee02d1e08afee88f54baec39ea78dc8a23c MISC:https://git.kernel.org/stable/c/32556ce93bc45c730829083cb60f95a2728ea48b URL:https://git.kernel.org/stable/c/32556ce93bc45c730829083cb60f95a2728ea48b MISC:https://git.kernel.org/stable/c/a2c8dc7e21803257e762b0bf067fd13e9c995da0 URL:https://git.kernel.org/stable/c/a2c8dc7e21803257e762b0bf067fd13e9c995da0
Assigning CNA
kernel.org
Date Record Created
20241021	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20241021)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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