Subject: [to-be-updated] vsprintf-ignore-arguments-to-%n.patch removed from -mm tree To: keescook@xxxxxxxxxxxx,dborkman@xxxxxxxxxx,jkosina@xxxxxxx,joe@xxxxxxxxxxx,olof@xxxxxxxxx,rmallon@xxxxxxxxx,stable@xxxxxxxxxxxxxxx,stepanm@xxxxxxxxxxxxxx,viro@xxxxxxxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx 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 <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 lib-vsprintf-add-%pt-format-specifier.patch binfmt_elfc-use-get_random_int-to-fix-entropy-depleting.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html