+ lib-kasprintfc-add-sanity-check-to-kvasprintf.patch added to -mm tree

* + lib-kasprintfc-add-sanity-check-to-kvasprintf.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/kasprintf.c: add sanity check to kvasprintf
has been added to the -mm tree.  Its filename is
     lib-kasprintfc-add-sanity-check-to-kvasprintf.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/lib-kasprintfc-add-sanity-check-to-kvasprintf.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/lib-kasprintfc-add-sanity-check-to-kvasprintf.patch

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------------------------------------------------------
From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Subject: lib/kasprintf.c: add sanity check to kvasprintf

kasprintf relies on being able to replay the formatting and getting
the same result (in particular, the same length). This will almost
always work, but it is possible that the object pointed to by a %s or
%p argument changed under us (so we might get truncated output). Add a
somewhat paranoid sanity check and let's see if it ever triggers.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
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: Kees Cook <keescook@chromium.org>
Cc: Maurizio Lombardi <mlombard@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/kasprintf.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff -puN lib/kasprintf.c~lib-kasprintfc-add-sanity-check-to-kvasprintf lib/kasprintf.c

--- a/lib/kasprintf.c~lib-kasprintfc-add-sanity-check-to-kvasprintf
+++ a/lib/kasprintf.c
@@ -13,19 +13,21 @@
 /* Simplified asprintf. */
 char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap)
 {
-	unsigned int len;
+	unsigned int first, second;
 	char *p;
 	va_list aq;
 
 	va_copy(aq, ap);
-	len = vsnprintf(NULL, 0, fmt, aq);
+	first = vsnprintf(NULL, 0, fmt, aq);
 	va_end(aq);
 
-	p = kmalloc_track_caller(len+1, gfp);
+	p = kmalloc_track_caller(first+1, gfp);
 	if (!p)
 		return NULL;
 
-	vsnprintf(p, len+1, fmt, ap);
+	second = vsnprintf(p, first+1, fmt, ap);
+	WARN(first != second, "different return values (%u and %u) from vsnprintf(\"%s\", ...)",
+	     first, second, fmt);
 
 	return p;
 }
_

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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