Andrii spotted that process_dynptr_func's rejection of incorrect
argument register type will print an error string where argument numbers
are not zero-indexed, unlike elsewhere in the verifier. Fix this by
subtracting 1 from regno. The same scenario exists for iterator
messages. Fix selftest error strings that match on the exact argument
number while we're at it to ensure clean bisection.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241203002235.3776418-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, KF_ARG_PTR_TO_ITER handling missed checking the reg->type and
ensuring it is PTR_TO_STACK. Instead of enforcing this in the caller of
process_iter_arg, move the check into it instead so that all callers
will gain the check by default. This is similar to process_dynptr_func.
An existing selftest in verifier_bits_iter.c fails due to this change,
but it's because it was passing a NULL pointer into iter_next helper and
getting an error further down the checks, but probably meant to pass an
uninitialized iterator on the stack (as is done in the subsequent test
below it). We will gain coverage for non-PTR_TO_STACK arguments in later
patches hence just change the declaration to zero-ed stack object.
Fixes: 06accc8779 ("bpf: add support for open-coded iterator loops")
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Tao Lyu <tao.lyu@epfl.ch>
[ Kartikeya: move check into process_iter_arg, rewrite commit log ]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241203000238.3602922-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
As reported by Byeonguk, the bad_words test in verifier_bits_iter.c
occasionally fails on s390 host. Quoting Ilya's explanation:
s390 kernel runs in a completely separate address space, there is no
user/kernel split at TASK_SIZE. The same address may be valid in both
the kernel and the user address spaces, there is no way to tell by
looking at it. The config option related to this property is
ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.
Also, unfortunately, 0 is a valid address in the s390 kernel address
space.
Fix the issue by using -4095 as the bad address for bits iterator, as
suggested by Ilya. Verify that bpf_iter_bits_new() returns -EINVAL for
NULL address and -EFAULT for bad address.
Fixes: ebafc1e535 ("selftests/bpf: Add three test cases for bits_iter")
Reported-by: Byeonguk Jeong <jungbu2855@gmail.com>
Closes: https://lore.kernel.org/bpf/ZycSXwjH4UTvx-Cn@ub22/
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20241105043057.3371482-1-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add more test cases for bits iterator:
(1) huge word test
Verify the multiplication overflow of nr_bits in bits_iter. Without
the overflow check, when nr_words is 67108865, nr_bits becomes 64,
causing bpf_probe_read_kernel_common() to corrupt the stack.
(2) max word test
Verify correct handling of maximum nr_words value (511).
(3) bad word test
Verify early termination of bits iteration when bits iterator
initialization fails.
Also rename bits_nomem to bits_too_big to better reflect its purpose.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241030100516.3633640-6-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add test cases for the bits iter:
- Positive cases
- Bit mask representing a single word (8-byte unit)
- Bit mask representing data spanning more than one word
- The index of the set bit
- Nagative cases
- bpf_iter_bits_destroy() is required after calling
bpf_iter_bits_new()
- bpf_iter_bits_destroy() can only destroy an initialized iter
- bpf_iter_bits_next() must use an initialized iter
- Bit mask representing zero words
- Bit mask representing fewer words than expected
- Case for ENOMEM
- Case for NULL pointer
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240517023034.48138-3-laoar.shao@gmail.com
