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Re: [patch] Fix for heap overflow in wscanf (BZ 16618)
- From: Florian Weimer <fweimer at redhat dot com>
- To: "Carlos O'Donell" <carlos at redhat dot com>, Paul Pluzhnikov <ppluzhnikov at google dot com>, Paul Eggert <eggert at cs dot ucla dot edu>
- Cc: Andreas Schwab <schwab at suse dot de>, Rich Felker <dalias at libc dot org>, libc-alpha at sourceware dot org
- Date: Fri, 06 Feb 2015 14:45:04 +0100
- Subject: Re: [patch] Fix for heap overflow in wscanf (BZ 16618)
- Authentication-results: sourceware.org; auth=none
- References: <CALoOobPgvuBLTk4GzOchr792MHNi1yLgsO5Jqf8MPvY+bk544Q at mail dot gmail dot com> <20150202050906 dot GF23507 at brightrain dot aerifal dot cx> <CALoOobP5yEqB-oKUvPVJm0znonYJ_iM1q_uFBNT2sRojBguJ-A at mail dot gmail dot com> <mvmiofkiqaj dot fsf at hawking dot suse dot de> <CALoOobPyDepfTFp=_y50iKHxAhKV8W+ZkUiV6e-2O=kgpT_08g at mail dot gmail dot com> <54CFCEB1 dot 8090301 at cs dot ucla dot edu> <CALoOobOqBGEp=Jv-sncnUzi6BVzypg9txr-Oh2OTQL7BFbuwSw at mail dot gmail dot com> <54D45696 dot 2020801 at redhat dot com>
On 02/06/2015 06:52 AM, Carlos O'Donell wrote:
> On 02/02/2015 02:52 PM, Paul Pluzhnikov wrote:
>> On Mon, Feb 2, 2015 at 11:23 AM, Paul Eggert <email@example.com> wrote:
>>> So, how about the attached (untested) patch to vfscanf.c instead? It's
>>> simpler. It does rely on realloc (wp, SIZE_MAX) returning NULL, but that's
>>> safe in glibc.
>> I like it. Re-tested.
>> Combined patch attached.
> Committed for 2.21.
> commit 5bd80bfe9ca0d955bfbbc002781bc7b01b6bcb06
> Author: Paul Pluzhnikov <firstname.lastname@example.org>
> Date: Fri Feb 6 00:30:42 2015 -0500
> CVE-2015-1472: wscanf allocates too little memory
> BZ #16618
> Under certain conditions wscanf can allocate too little memory for the
> to-be-scanned arguments and overflow the allocated buffer. The
> implementation now correctly computes the required buffer size when
> using malloc.
> A regression test was added to tst-sscanf.
I think this fixes as CVE-2015-1473 as well, which was assigned for the
inconsistent use of __libc_use_alloca (even though no application impact
had been demonstrated).
Florian Weimer / Red Hat Product Security