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[PATCH v2][BZ #14286] Fix integer overflow in vfwprintf.
- From: OndÅej BÃlka <neleai at seznam dot cz>
- To: Andreas Schwab <schwab at suse dot de>
- Cc: libc-alpha at sourceware dot org
- Date: Mon, 21 Oct 2013 11:38:37 +0200
- Subject: [PATCH v2][BZ #14286] Fix integer overflow in vfwprintf.
- Authentication-results: sourceware.org; auth=none
- References: <20131021082701 dot GA22363 at domone dot podge> <mvmsivv805x dot fsf at hawking dot suse dot de>
On Mon, Oct 21, 2013 at 11:04:42AM +0200, Andreas Schwab wrote:
> OndÅej BÃlka <neleai@seznam.cz> writes:
>
> > [BZ #14286]
> > * stdio-common/vfprintf.c: Fix integer overflow.
>
> s/Fix/Check for/
>
done.
> > diff --git a/stdio-common/vfprintf.c b/stdio-common/vfprintf.c
> > index 8cd7a85..ba6b6d1 100644
> > --- a/stdio-common/vfprintf.c
> > +++ b/stdio-common/vfprintf.c
> > @@ -1067,7 +1067,12 @@ vfprintf (FILE *s, const CHAR_T *format, va_list ap)
> > /* Allocate dynamically an array which definitely is long \
> > enough for the wide character version. Each byte in the \
> > multi-byte string can produce at most one wide character. */ \
> > - if (__libc_use_alloca (len * sizeof (wchar_t))) \
> > + if (len > SIZE_MAX / sizeof (wchar_t)) \
> > + { \
> > + done = -1; \
> > + goto all_done; \
>
> You need to set errno. Use __glibc_unlikely.
>
ok, but errno handling confused me. I copied that from case when malloc
fails that if I read code correctly does not set ENOMEM. Should we add
additional errnos there?
[BZ #14286]
* stdio-common/vfprintf.c: Check for integer overflow.
diff --git a/stdio-common/vfprintf.c b/stdio-common/vfprintf.c
index 8cd7a85..42a7bb2 100644
--- a/stdio-common/vfprintf.c
+++ b/stdio-common/vfprintf.c
@@ -1067,7 +1067,13 @@ vfprintf (FILE *s, const CHAR_T *format, va_list ap)
/* Allocate dynamically an array which definitely is long \
enough for the wide character version. Each byte in the \
multi-byte string can produce at most one wide character. */ \
- if (__libc_use_alloca (len * sizeof (wchar_t))) \
+ if (__glibc_unlikely (len > SIZE_MAX / sizeof (wchar_t))) \
+ { \
+ __set_errno (EOVERFLOW); \
+ done = -1; \
+ goto all_done; \
+ } \
+ else if (__libc_use_alloca (len * sizeof (wchar_t))) \
string = (CHAR_T *) alloca (len * sizeof (wchar_t)); \
else if ((string = (CHAR_T *) malloc (len * sizeof (wchar_t))) \
== NULL) \