[PATCH AUTOSEL 6.10 06/70] bpftool: Fix undefined behavior caused by shifting into the sign bit

Sasha Levin
2024-10-04T18:22:12Z

From: Kuan-Wei Chiu <visitorckw@gmail.com>

[ Upstream commit 4cdc0e4ce5e893bc92255f5f734d983012f2bc2e ]

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: Kuan-Wei Chiu <visitorckw@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/bpf/20240908140009.3149781-1-visitorckw@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/bpf/bpftool/net.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
index 0ad684e810f34..0f2106218e1f0 100644
--- a/tools/bpf/bpftool/net.c
+++ b/tools/bpf/bpftool/net.c
@@ -482,9 +482,9 @@ 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("");
}
@@ -493,9 +493,9 @@ 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("");
}
--
2.43.0