bpf: Mark bpf prog stack with kmsan_unposion_memory in interpreter mode
syzbot reported uninit memory usages during map_{lookup,delete}_elem.
==========
BUG: KMSAN: uninit-value in __dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline]
BUG: KMSAN: uninit-value in dev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796
__dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline]
dev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796
____bpf_map_lookup_elem kernel/bpf/helpers.c:42 [inline]
bpf_map_lookup_elem+0x5c/0x80 kernel/bpf/helpers.c:38
___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997
__bpf_prog_run256+0xb5/0xe0 kernel/bpf/core.c:2237
==========
The reproducer should be in the interpreter mode.
The C reproducer is trying to run the following bpf prog:
0: (18) r0 = 0x0
2: (18) r1 = map[id:49]
4: (b7) r8 = 16777216
5: (7b) *(u64 *)(r10 -8) = r8
6: (bf) r2 = r10
7: (07) r2 += -229
^^^^^^^^^^
8: (b7) r3 = 8
9: (b7) r4 = 0
10: (85) call dev_map_lookup_elem#1543472
11: (95) exit
It is due to the "void *key" (r2) passed to the helper. bpf allows uninit
stack memory access for bpf prog with the right privileges. This patch
uses kmsan_unpoison_memory() to mark the stack as initialized.
This should address different syzbot reports on the uninit "void *key"
argument during map_{lookup,delete}_elem.
Metrics
Affected Vendors & Products
Wed, 11 Sep 2024 13:30:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Metrics |
ssvc
|
Thu, 05 Sep 2024 18:00:00 +0000
Type | Values Removed | Values Added |
---|---|---|
First Time appeared |
Linux
Linux linux Kernel |
|
Weaknesses | CWE-908 | |
CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
Vendors & Products |
Linux
Linux linux Kernel |
|
Metrics |
cvssV3_1
|
cvssV3_1
|
Mon, 19 Aug 2024 22:30:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Weaknesses | CWE-120 | |
Metrics |
cvssV3_1
|
cvssV3_1
|

Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-05-04T09:22:09.742Z
Reserved: 2024-07-29T15:50:41.166Z
Link: CVE-2024-42063

Updated: 2024-08-02T04:54:31.920Z

Status : Modified
Published: 2024-07-29T16:15:06.053
Modified: 2024-11-21T09:33:30.810
Link: CVE-2024-42063


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