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

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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@xxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 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@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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