From: Kuan-Wei Chiu <visitorckw@gmail.com>
Date: Sun, 8 Sep 2024 14:00:09 +0000 (+0800)
Subject: bpftool: Fix undefined behavior caused by shifting into the sign bit
X-Git-Tag: microblaze-v6.13~115^2~30
X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=4cdc0e4ce5e893bc92255f5f734d983012f2bc2e;p=linux-2.6-microblaze.git

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: 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
---

diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
index 2a51f1c25732..3c50fc66bb4a 100644
--- a/tools/bpf/bpftool/net.c
+++ b/tools/bpf/bpftool/net.c
@@ -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("");
 			}