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
Configurations
Configuration 1 (hide)
|
History
14 Dec 2024, 21:15
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
23 Oct 2024, 16:48
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.1 |
| CWE | NVD-CWE-noinfo | |
| First Time |
Linux
Linux linux Kernel |
|
| CPE | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| References | () https://git.kernel.org/stable/c/1e75d25133158b525e0456876e9bcfd6b2993fd5 - Patch | |
| References | () https://git.kernel.org/stable/c/a2c8dc7e21803257e762b0bf067fd13e9c995da0 - Patch | |
| References | () https://git.kernel.org/stable/c/2ed98ee02d1e08afee88f54baec39ea78dc8a23c - Patch | |
| References | () https://git.kernel.org/stable/c/32556ce93bc45c730829083cb60f95a2728ea48b - Patch |
21 Oct 2024, 13:15
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2024-10-21 13:15
Updated : 2024-12-14 21:15
NVD link : CVE-2024-49861
Mitre link : CVE-2024-49861
JSON object : View
Products Affected
linux
- linux_kernel
CWE