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From:   Azeem Shaikh <azeemshaikh38@gmail.com>
To:     Russell King <linux@armlinux.org.uk>
Cc:     linux-hardening@vger.kernel.org,
        Azeem Shaikh <azeemshaikh38@gmail.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>,
        Linus Walleij <linus.walleij@linaro.org>,
        Amit Daniel Kachhap <amit.kachhap@arm.com>,
        Ard Biesheuvel <ardb@kernel.org>
Subject: [PATCH] ARM: Replace all non-returning strlcpy with strscpy
Date:   Tue, 30 May 2023 15:55:01 +0000
Message-ID: <20230530155501.222213-1-azeemshaikh38@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
---
 arch/arm/kernel/atags_parse.c |    4 ++--
 arch/arm/kernel/setup.c       |    2 +-
 arch/arm/kernel/vdso.c        |    2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/atags_parse.c b/arch/arm/kernel/atags_parse.c
index 373b61f9a4f0..33f6eb5213a5 100644
--- a/arch/arm/kernel/atags_parse.c
+++ b/arch/arm/kernel/atags_parse.c
@@ -127,7 +127,7 @@ static int __init parse_tag_cmdline(const struct tag *tag)
 #elif defined(CONFIG_CMDLINE_FORCE)
 	pr_warn("Ignoring tag cmdline (using the default kernel command line)\n");
 #else
-	strlcpy(default_command_line, tag->u.cmdline.cmdline,
+	strscpy(default_command_line, tag->u.cmdline.cmdline,
 		COMMAND_LINE_SIZE);
 #endif
 	return 0;
@@ -224,7 +224,7 @@ setup_machine_tags(void *atags_vaddr, unsigned int machine_nr)
 	}
 
 	/* parse_early_param needs a boot_command_line */
-	strlcpy(boot_command_line, from, COMMAND_LINE_SIZE);
+	strscpy(boot_command_line, from, COMMAND_LINE_SIZE);
 
 	return mdesc;
 }
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 75cd4699e7b3..3048a685ea79 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -1142,7 +1142,7 @@ void __init setup_arch(char **cmdline_p)
 	setup_initial_init_mm(_text, _etext, _edata, _end);
 
 	/* populate cmd_line too for later use, preserving boot_command_line */
-	strlcpy(cmd_line, boot_command_line, COMMAND_LINE_SIZE);
+	strscpy(cmd_line, boot_command_line, COMMAND_LINE_SIZE);
 	*cmdline_p = cmd_line;
 
 	early_fixmap_init();
diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
index 3408269d19c7..f297d66a8a76 100644
--- a/arch/arm/kernel/vdso.c
+++ b/arch/arm/kernel/vdso.c
@@ -135,7 +135,7 @@ static Elf32_Sym * __init find_symbol(struct elfinfo *lib, const char *symname)
 
 		if (lib->dynsym[i].st_name == 0)
 			continue;
-		strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
+		strscpy(name, lib->dynstr + lib->dynsym[i].st_name,
 			MAX_SYMNAME);
 		c = strchr(name, '@');
 		if (c)