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@xxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxxxxxxxxxxx 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-test_printfc-dont-bug.patch
lib-test_printfc-check-for-out-of-bound-writes.patch
lib-test_printfc-add-a-few-string-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
lib-kasprintfc-add-sanity-check-to-kvasprintf.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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