linux-kernel - [PATCH v1 1/2] selftest/kexec: fix "ignored null byte in input" warning

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Date:   Wed, 22 Dec 2021 16:30:51 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     linux-integrity@...r.kernel.org
Cc:     Petr Vorel <pvorel@...e.cz>,
        Nageswara Sastry <rnsastry@...ux.ibm.com>,
        Mimi Zohar <zohar@...ux.ibm.com>, Takashi Iwai <tiwai@...e.de>,
        Joey Lee <jlee@...e.com>, Shuah Khan <shuah@...nel.org>,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1 1/2] selftest/kexec: fix "ignored null byte in input" warning

Instead of assigning the string to a variable, which might contain a
null character, redirect the output and grep for the string directly.

Signed-off-by: Mimi Zohar <zohar@...ux.ibm.com>
---
Comment: this patch was previously posted as part of Nageswara's larger
 patch set.

 tools/testing/selftests/kexec/test_kexec_file_load.sh | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kexec/test_kexec_file_load.sh b/tools/testing/selftests/kexec/test_kexec_file_load.sh
index 2ff600388c30..99f6fc23ee31 100755
--- a/tools/testing/selftests/kexec/test_kexec_file_load.sh
+++ b/tools/testing/selftests/kexec/test_kexec_file_load.sh
@@ -97,10 +97,11 @@ check_for_imasig()
 check_for_modsig()
 {
 	local module_sig_string="~Module signature appended~"
-	local sig="$(tail --bytes $((${#module_sig_string} + 1)) $KERNEL_IMAGE)"
 	local ret=0
 
-	if [ "$sig" == "$module_sig_string" ]; then
+	tail --bytes $((${#module_sig_string} + 1)) $KERNEL_IMAGE | \
+		grep -q "$module_sig_string"
+	if [ $? -eq 0 ]; then
 		ret=1
 		log_info "kexec kernel image modsig signed"
 	else
-- 
2.27.0