hid_bpf_get_data() exposes a pointer into the HID-BPF context data when
the caller-provided offset and size fit inside ctx->allocated_size.
The helper currently checks that range with:
rdwr_buf_size + offset > ctx->allocated_size
Since both operands are unsigned, a very large size can wrap the sum and
make an out-of-range request look valid.
Patch 1 changes the helper to reject offset values beyond the allocation
and then compare the requested size against the remaining bytes.
Patch 2 adds a HID-BPF regression check that asks hid_bpf_get_data() for
offset 2 and size ~0ULL from an rdesc_fixup callback and expects NULL.
It also adds KHDR_INCLUDES to the HID selftest build so the userspace
test sees current kernel UAPI HID definitions.
Validation, rebased and tested on bpf-next master e4287bf34f97
("selftests/bpf: Work around llvm stack overflow in crypto progs"):
git diff --check e4287bf34f97..HEAD: OK
scripts/checkpatch.pl --strict -g e4287bf34f97..HEAD: OK
make
O=/root/ebpf-verifier-bug-detection/kernel-build/bpf-next-hidbpf-20260616 \
drivers/hid/bpf/hid_bpf_dispatch.o: OK
make -C tools/testing/selftests/hid \
O=/root/ebpf-verifier-bug-detection/kernel-build/bpf-next-hidbpf-20260616 \
OUTPUT=/tmp/hid-selftest-026-v2 \
VMLINUX_BTF=/root/ebpf-verifier-bug-detection/kernel-build/bpf-next-hidbpf-20260616/vmlinux
\
KHDR_INCLUDES=-isystem
/root/ebpf-verifier-bug-detection/kernel-build/bpf-next-hidbpf-20260616/usr/include
\
hid_bpf: OK
Changes in v2:
- Drop the temporary data variable around the overflow
hid_bpf_get_data() call in the selftest callback.
- Correct the Fixes tag to commit 658ee5a64fcf ("HID: bpf: allocate
data memory for device_event BPF programs").
v1:
https://lore.kernel.org/bpf/[email protected]/
Yiyang Chen (2):
HID: bpf: Fix hid_bpf_get_data() range check
selftests/hid: Cover hid_bpf_get_data() size overflow
drivers/hid/bpf/hid_bpf_dispatch.c | 3 ++-
tools/testing/selftests/hid/Makefile | 2 +-
tools/testing/selftests/hid/hid_bpf.c | 11 +++++++++++
tools/testing/selftests/hid/progs/hid.c | 15 +++++++++++++++
4 files changed, 29 insertions(+), 2 deletions(-)
base-commit: e4287bf34f97a88c7d9322f5bde828724c073a6b
--
2.34.1
