Commit 4cdc0e4c authored by Kuan-Wei Chiu's avatar Kuan-Wei Chiu Committed by Andrii Nakryiko
Browse files

bpftool: Fix undefined behavior caused by shifting into the sign bit 



Replace shifts of '1' with '1U' in bitwise operations within
__show_dev_tc_bpf() to prevent undefined behavior caused by shifting
into the sign bit of a signed integer. By using '1U', the operations
are explicitly performed on unsigned integers, avoiding potential
integer overflow or sign-related issues.

Signed-off-by: default avatarKuan-Wei Chiu <visitorckw@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarQuentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/bpf/20240908140009.3149781-1-visitorckw@gmail.com
parent 12707b91

tools/bpf/bpftool/net.c

+4 −4
Original line number Diff line number Diff line
@@ -486,9 +486,9 @@ static void __show_dev_tc_bpf(const struct ip_devname_ifindex *dev, 
		if (prog_flags[i] || json_output) {

			NET_START_ARRAY("prog_flags", "%s ");

			for (j = 0; prog_flags[i] && j < 32; j++) {

				if (!(prog_flags[i] & (1 << j)))

				if (!(prog_flags[i] & (1U << j)))

					continue;

				NET_DUMP_UINT_ONLY(1 << j);

				NET_DUMP_UINT_ONLY(1U << j);

			}

			NET_END_ARRAY("");

		}
@@ -497,9 +497,9 @@ static void __show_dev_tc_bpf(const struct ip_devname_ifindex *dev, 
			if (link_flags[i] || json_output) {

				NET_START_ARRAY("link_flags", "%s ");

				for (j = 0; link_flags[i] && j < 32; j++) {

					if (!(link_flags[i] & (1 << j)))

					if (!(link_flags[i] & (1U << j)))

						continue;

					NET_DUMP_UINT_ONLY(1 << j);

					NET_DUMP_UINT_ONLY(1U << j);

				}

				NET_END_ARRAY("");

			}