[PATCH bpf v5 0/2] bpf: Fix OOB in pcpu_init_value and add a test

[xulang <xulang@uniontech.com>]

From: Lang Xu <xulang@uniontech.com>

Fix OOB read when copying element from a BPF_MAP_TYPE_CGROUP_STORAGE
map to another pcpu map with the same value_size that is not rounded
up to 8 bytes, and add a test case to reproduce the issue.

The root cause is that pcpu_init_value() uses copy_map_value_long() which
rounds up the copy size to 8 bytes, but CGROUP_STORAGE map values are not
8-byte aligned (e.g., 4-byte). This causes a 4-byte OOB read when
the copy is performed.

Lang Xu (2):
  bpf: Fix OOB in pcpu_init_value
  selftests/bpf: Add test for cgroup storage OOB read

Signed-off-by: Lang Xu <xulang@uniontech.com>
---
Changes since v4:
- Make the summary phrase of the cover different from patch 1
- Fix patch series format issues

Changes since v3:
- nothing changed, just resend the patch series manually.
  There is something wrong with my email server(Message-ID overrided).

Changes since v2:
- Fix patch series format issues
- Instead of aligning CGROUP_STORAGE allocation,
  fix it by replacing copy_map_value_long with copy_map_value in
  pcpu_init_value

Changes since v1:
- Add self-test program to reproduce the issue

base-commit: 7aaa8047eafd ("Linux 7.0-rc6")

 kernel/bpf/hashtab.c                               |  2 +-
 tools/testing/selftests/bpf/prog_tests/cgroup_storage.c | 42 +++++++++++++++++++++
 tools/testing/selftests/bpf/progs/cgroup_storage.c      | 43 ++++++++++++++++++++++
 3 files changed, 86 insertions(+), 1 deletion(-)

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2.51.0