linux-kernel - [tip: x86/kaslr] x86/kaslr: Replace strlen() with strnlen()

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Date:   Thu, 06 Aug 2020 23:38:49 -0000
From:   "tip-bot2 for Arvind Sankar" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Arvind Sankar <nivedita@...m.mit.edu>,
        Ingo Molnar <mingo@...nel.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: x86/kaslr] x86/kaslr: Replace strlen() with strnlen()

The following commit has been merged into the x86/kaslr branch of tip:

Commit-ID:     76167e5c5457aee8fba3edc5b8554183696fc94d
Gitweb:        https://git.kernel.org/tip/76167e5c5457aee8fba3edc5b8554183696fc94d
Author:        Arvind Sankar <nivedita@...m.mit.edu>
AuthorDate:    Sun, 02 Aug 2020 21:15:34 -04:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Thu, 06 Aug 2020 17:03:19 +02:00

x86/kaslr: Replace strlen() with strnlen()

strnlen is safer in case the command line is not NUL-terminated.

Signed-off-by: Arvind Sankar <nivedita@...m.mit.edu>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Link: https://lore.kernel.org/r/20200803011534.730645-2-nivedita@alum.mit.edu
---
 arch/x86/boot/compressed/kaslr.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 735fcb2..6d39743 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -43,6 +43,10 @@
 #define STATIC
 #include <linux/decompress/mm.h>
 
+#define _SETUP
+#include <asm/setup.h>	/* For COMMAND_LINE_SIZE */
+#undef _SETUP
+
 #ifdef CONFIG_X86_5LEVEL
 unsigned int __pgtable_l5_enabled;
 unsigned int pgdir_shift __ro_after_init = 39;
@@ -278,7 +282,7 @@ static void handle_mem_options(void)
 	if (!args)
 		return;
 
-	len = strlen(args);
+	len = strnlen(args, COMMAND_LINE_SIZE-1);
 	tmp_cmdline = malloc(len + 1);
 	if (!tmp_cmdline)
 		error("Failed to allocate space for tmp_cmdline");
@@ -425,7 +429,7 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
 	cmd_line = get_cmd_line_ptr();
 	/* Calculate size of cmd_line. */
 	if (cmd_line) {
-		cmd_line_size = strlen((char *)cmd_line) + 1;
+		cmd_line_size = strnlen((char *)cmd_line, COMMAND_LINE_SIZE-1) + 1;
 		mem_avoid[MEM_AVOID_CMDLINE].start = cmd_line;
 		mem_avoid[MEM_AVOID_CMDLINE].size = cmd_line_size;
 		add_identity_map(mem_avoid[MEM_AVOID_CMDLINE].start,