Subject: [to-be-updated] vsprintf-ignore-arguments-to-%n.patch removed from -mm 
tree
To: 
[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected]
From: [email protected]
Date: Tue, 28 Jan 2014 13:30:21 -0800


The patch titled
     Subject: vsprintf: ignore arguments to %n
has been removed from the -mm tree.  Its filename was
     vsprintf-ignore-arguments-to-%n.patch

This patch was dropped because an updated version will be merged

------------------------------------------------------
From: Kees Cook <[email protected]>
Subject: vsprintf: ignore arguments to %n

If arguments are consumed without output when encountering %n, it could be
used to benefit or improve information leak attacks that were exposed via
a limited size buffer.  Since %n is not used by the kernel, there is no
reason to make an info leak attack any easier.

Signed-off-by: Kees Cook <[email protected]>
Cc: Ryan Mallon <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Olof Johansson <[email protected]>
Cc: Stepan Moskovchenko <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: <[email protected]>    [3.13+]
Signed-off-by: Andrew Morton <[email protected]>
---

 lib/vsprintf.c |   10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff -puN lib/vsprintf.c~vsprintf-ignore-arguments-to-%n lib/vsprintf.c
--- a/lib/vsprintf.c~vsprintf-ignore-arguments-to-%n
+++ a/lib/vsprintf.c
@@ -1735,14 +1735,10 @@ int vsnprintf(char *buf, size_t size, co
                case FORMAT_TYPE_NRCHARS: {
                        /*
                         * Since %n poses a greater security risk than
-                        * utility, ignore %n and skip its argument.
+                        * utility, it should not be implemented. Instead,
+                        * when encountering %n, ignore the arguments.
                         */
-                       void *skip_arg;
-
-                       WARN_ONCE(1, "Please remove ignored %%n in '%s'\n",
-                                       old_fmt);
-
-                       skip_arg = va_arg(args, void *);
+                       WARN_ONCE(1, "Ignored %%n in '%s'\n", old_fmt);
                        break;
                }
 
_

Patches currently in -mm which might be from [email protected] are

origin.patch
lib-vsprintf-add-%pt-format-specifier.patch
binfmt_elfc-use-get_random_int-to-fix-entropy-depleting.patch
linux-next.patch

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