Subject: + vsprintf-ignore-arguments-to-%n.patch added to -mm tree
To: keescook@xxxxxxxxxxxx,dborkman@xxxxxxxxxx,jkosina@xxxxxxx,joe@xxxxxxxxxxx,olof@xxxxxxxxx,rmallon@xxxxxxxxx,stable@xxxxxxxxxxxxxxx,stepanm@xxxxxxxxxxxxxx,viro@xxxxxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 28 Jan 2014 12:05:40 -0800
The patch titled
Subject: vsprintf: ignore arguments to %n
has been added to the -mm tree. Its filename is
vsprintf-ignore-arguments-to-%n.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/vsprintf-ignore-arguments-to-%n.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/vsprintf-ignore-arguments-to-%n.patch
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------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
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 <keescook@xxxxxxxxxxxx>
Cc: Ryan Mallon <rmallon@xxxxxxxxx>
Cc: Jiri Kosina <jkosina@xxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Olof Johansson <olof@xxxxxxxxx>
Cc: Stepan Moskovchenko <stepanm@xxxxxxxxxxxxxx>
Cc: Daniel Borkmann <dborkman@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [3.13+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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 keescook@xxxxxxxxxxxx are
origin.patch
vsprintf-ignore-arguments-to-%n.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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