88 lines
3 KiB
Diff
88 lines
3 KiB
Diff
From 47eddcfc6859f269bb3cfaf95d5b33502cafd9ec Mon Sep 17 00:00:00 2001
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From: Michael Chang <mchang@suse.com>
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Date: Mon, 21 Jun 2021 05:11:18 +0000
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Subject: [PATCH] 30_uefi-firmware: fix printf format with null byte
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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On a Raspberry Pi 4, the OsIndications variable is set as following
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$ od -An -t u1 /sys/firmware/efi/efivars/OsIndicationsSupported-8be4df61-93ca-11d2-aa0d-00e098032b8c
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6 0 0 0 0 0 0 0 0 0 0 0
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The fifth byte indicates there's no boot to uefi firmware support as no
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bit is set. However the /etc/grub.d/30_uefi-firmware mistakenly detects
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that from the grub-mkconfig output.
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/etc/grub.d/30_uefi-firmware: line 34: warning: command substitution: ignored null byte in input
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Adding boot menu entry for UEFI Firmware Settings ...
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The warning has dictated that the null byte is ignored from the printf
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input arguments so that the expression of
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rintf 0x%x \'"$(cat $OS_INDICATIONS | cut -b5)"\')
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becomes
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printf 0x%x \'""\'
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0x27
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The numeric value of trailing character \' is outputted instead of the
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null byte.
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From the printf manual, there's description to the synax of formatting
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the numeric value ouput of a character.
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"If the leading character of a numeric argument is ‘"’ or ‘'’ then its
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value is the numeric value of the immediately following character. Any
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remaining characters are silently ignored if the POSIXLY_CORRECT
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environment variable is set; otherwise, a warning is printed. For
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example, ‘printf "%d" "'a"’ outputs ‘97’ on hosts that use the ASCII
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character set, since ‘a’ has the numeric value 97 in ASCII."
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From the descrption the trailing \' appears to be superfluous and should
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get removed to have correct output.
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printf 0x%x \'""
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0x0
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In additon to suppress the warning message of ignored null byte in
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input, we can delete it so an empty string is used.
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To illustrate the problem using echo as example
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printf 0x%x \'"$(echo -e '\x00')"
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-bash: warning: command substitution: ignored null byte in input
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0x0
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And here using tr to delete the null character
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printf 0x%x \'"$(echo -e '\x00'| tr -d '\000')"
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The expression above is substituted to
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printf 0x%x \'""
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0x0
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Signed-off-by: Michael Chang <mchang@suse.com>
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---
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util/grub.d/30_uefi-firmware.in | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/util/grub.d/30_uefi-firmware.in b/util/grub.d/30_uefi-firmware.in
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index d344d3883..d069f2727 100644
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--- a/util/grub.d/30_uefi-firmware.in
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+++ b/util/grub.d/30_uefi-firmware.in
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@@ -31,7 +31,7 @@ EFI_GLOBAL_VARIABLE=8be4df61-93ca-11d2-aa0d-00e098032b8c
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OS_INDICATIONS="$EFI_VARS_DIR/OsIndicationsSupported-$EFI_GLOBAL_VARIABLE"
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if [ -e "$OS_INDICATIONS" ] && \
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- [ "$(( $(printf 0x%x \'"$(cat $OS_INDICATIONS | cut -b5)"\') & 1 ))" = 1 ]; then
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+ [ "$(( $(printf 0x%x \'"$(cat $OS_INDICATIONS | cut -b5 | tr -d '\000')") & 1 ))" = 1 ]; then
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LABEL="UEFI Firmware Settings"
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gettext_printf "Adding boot menu entry for UEFI Firmware Settings ...\n" >&2
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--
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2.26.2
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