+ lib-test_printfc-check-for-out-of-bound-writes.patch added to -mm tree

* + lib-test_printfc-check-for-out-of-bound-writes.patch added to -mm tree
@ 2015-12-03 23:35 akpm
  0 siblings, 0 replies; 2+ messages in thread
From: akpm @ 2015-12-03 23:35 UTC (permalink / raw)
  To: linux, andriy.shevchenko, joe, keescook, mingo, mlombard, tj,
	viro, mm-commits


The patch titled
     Subject: lib/test_printf.c: check for out-of-bound writes
has been added to the -mm tree.  Its filename is
     lib-test_printfc-check-for-out-of-bound-writes.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/lib-test_printfc-check-for-out-of-bound-writes.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/lib-test_printfc-check-for-out-of-bound-writes.patch

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*** Remember to use Documentation/SubmitChecklist when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Subject: lib/test_printf.c: check for out-of-bound writes

Add a few padding bytes on either side of the test buffer, and check
that these (and the part of the buffer not used) are untouched by
vsnprintf.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Maurizio Lombardi <mlombard@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/test_printf.c |   24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff -puN lib/test_printf.c~lib-test_printfc-check-for-out-of-bound-writes lib/test_printf.c

--- a/lib/test_printf.c~lib-test_printfc-check-for-out-of-bound-writes
+++ a/lib/test_printf.c
@@ -16,6 +16,7 @@
 #include <linux/in.h>
 
 #define BUF_SIZE 256
+#define PAD_SIZE 16
 #define FILL_CHAR '$'
 
 #define PTR1 ((void*)0x01234567)
@@ -39,6 +40,7 @@
 static unsigned total_tests __initdata;
 static unsigned failed_tests __initdata;
 static char *test_buffer __initdata;
+static char *alloced_buffer __initdata;
 
 static int __printf(4, 0) __init
 do_test(int bufsize, const char *expect, int elen,
@@ -49,7 +51,7 @@ do_test(int bufsize, const char *expect,
 
 	total_tests++;
 
-	memset(test_buffer, FILL_CHAR, BUF_SIZE);
+	memset(alloced_buffer, FILL_CHAR, BUF_SIZE + 2*PAD_SIZE);
 	va_copy(aq, ap);
 	ret = vsnprintf(test_buffer, bufsize, fmt, aq);
 	va_end(aq);
@@ -60,8 +62,13 @@ do_test(int bufsize, const char *expect,
 		return 1;
 	}
 
+	if (memchr_inv(alloced_buffer, FILL_CHAR, PAD_SIZE)) {
+		pr_warn("vsnprintf(buf, %d, \"%s\", ...) wrote before buffer\n", bufsize, fmt);
+		return 1;
+	}
+
 	if (!bufsize) {
-		if (memchr_inv(test_buffer, FILL_CHAR, BUF_SIZE)) {
+		if (memchr_inv(test_buffer, FILL_CHAR, BUF_SIZE + PAD_SIZE)) {
 			pr_warn("vsnprintf(buf, 0, \"%s\", ...) wrote to buffer\n",
 				fmt);
 			return 1;
@@ -76,6 +83,12 @@ do_test(int bufsize, const char *expect,
 		return 1;
 	}
 
+	if (memchr_inv(test_buffer + written + 1, FILL_CHAR, BUF_SIZE + PAD_SIZE - (written + 1))) {
+		pr_warn("vsnprintf(buf, %d, \"%s\", ...) wrote beyond the nul-terminator\n",
+			bufsize, fmt);
+		return 1;
+	}
+
 	if (memcmp(test_buffer, expect, written)) {
 		pr_warn("vsnprintf(buf, %d, \"%s\", ...) wrote '%s', expected '%.*s'\n",
 			bufsize, fmt, test_buffer, written, expect);
@@ -342,16 +355,17 @@ test_pointer(void)
 static int __init
 test_printf_init(void)
 {
-	test_buffer = kmalloc(BUF_SIZE, GFP_KERNEL);
-	if (!test_buffer)
+	alloced_buffer = kmalloc(BUF_SIZE + 2*PAD_SIZE, GFP_KERNEL);
+	if (!alloced_buffer)
 		return -ENOMEM;
+	test_buffer = alloced_buffer + PAD_SIZE;
 
 	test_basic();
 	test_number();
 	test_string();
 	test_pointer();
 
-	kfree(test_buffer);
+	kfree(alloced_buffer);
 
 	if (failed_tests == 0)
 		pr_info("all %u tests passed\n", total_tests);
_

Patches currently in -mm which might be from linux@rasmusvillemoes.dk are

lib-vsprintfc-pull-out-padding-code-from-dentry_name.patch
lib-vsprintfc-move-string-below-widen_string.patch
lib-vsprintfc-eliminate-potential-race-in-string.patch
lib-vsprintfc-expand-field_width-to-24-bits.patch
lib-vsprintfc-help-gcc-make-number-smaller.patch
lib-vsprintfc-warn-about-too-large-precisions-and-field-widths.patch
lib-kasprintfc-add-sanity-check-to-kvasprintf.patch
lib-test_printfc-dont-bug.patch
lib-test_printfc-check-for-out-of-bound-writes.patch
lib-test_printfc-test-precision-quirks.patch
lib-test_printfc-add-a-few-number-tests.patch
lib-test_printfc-account-for-kvasprintf-tests.patch
lib-test_printfc-add-test-for-large-bitmaps.patch
lib-test_printfc-test-dentry-printing.patch
powerpc-fadump-rename-cpu_online_mask-member-of-struct-fadump_crash_info_header.patch
kernel-cpuc-change-type-of-cpu_possible_bits-and-friends.patch
kernel-cpuc-export-__cpu__mask.patch
drivers-base-cpuc-use-__cpu__mask-directly.patch
kernel-cpuc-eliminate-cpu__mask.patch
kernel-cpuc-make-set_cpu_-static-inlines.patch


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