bpf: fix bpffs bitfield pretty print (17e3ac81) · Commits · 戴 / test

Commit ("bpf: btf: fix struct/union/fwd types with kind_flag") introduced kind_flag and used bitfield_size in the btf_member to directly pretty print member values. The commit contained a bug where the incorrect parameters could be passed to function btf_bitfield_seq_show(). The bits_offset parameter in the function expects a value less than 8. Instead, the member offset in the structure is passed. The below is btf_bitfield_seq_show() func signature: void btf_bitfield_seq_show(void *data, u8 bits_offset, u8 nr_bits, struct seq_file *m) both bits_offset and nr_bits are u8 type. If the bitfield member offset is greater than 256, incorrect value will be printed. This patch fixed the issue by calculating correct proper data offset and bits_offset similar to non kind_flag case. Fixes: ("bpf: btf: fix struct/union/fwd types with kind_flag") Acked-by:

Martin KaFai Lau <kafai@fb.com> Signed-off-by:

Yonghong Song <yhs@fb.com> Signed-off-by:

Daniel Borkmann <daniel@iogearbox.net>

kernel/bpf/btf.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -1219,8 +1219,6 @@ static void btf_bitfield_seq_show(void *data, u8 bits_offset,
		u8 nr_copy_bits;
		u64 print_num;

		data += BITS_ROUNDDOWN_BYTES(bits_offset);
		bits_offset = BITS_PER_BYTE_MASKED(bits_offset);
		nr_copy_bits = nr_bits + bits_offset;
		nr_copy_bytes = BITS_ROUNDUP_BYTES(nr_copy_bits);

		@@ -1255,7 +1253,9 @@ static void btf_int_bits_seq_show(const struct btf *btf,
		* BTF_INT_OFFSET() cannot exceed 64 bits.
		*/
		total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data);
		btf_bitfield_seq_show(data, total_bits_offset, nr_bits, m);
		data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
		bits_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
		btf_bitfield_seq_show(data, bits_offset, nr_bits, m);
		}

		static void btf_int_seq_show(const struct btf btf, const struct btf_type t,
		@@ -2001,12 +2001,12 @@ static void btf_struct_seq_show(const struct btf btf, const struct btf_type t,

		member_offset = btf_member_bit_offset(t, member);
		bitfield_size = btf_member_bitfield_size(t, member);
		bytes_offset = BITS_ROUNDDOWN_BYTES(member_offset);
		bits8_offset = BITS_PER_BYTE_MASKED(member_offset);
		if (bitfield_size) {
		btf_bitfield_seq_show(data, member_offset,
		btf_bitfield_seq_show(data + bytes_offset, bits8_offset,
		bitfield_size, m);
		} else {
		bytes_offset = BITS_ROUNDDOWN_BYTES(member_offset);
		bits8_offset = BITS_PER_BYTE_MASKED(member_offset);
		ops = btf_type_ops(member_type);
		ops->seq_show(btf, member_type, member->type,
		data + bytes_offset, bits8_offset, m);

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