Bug 192834 – media-libs/libsndfile-1.0.17 Heap-based buffer overflow in flac.c (CVE-2007-4974)

• Status: RESOLVED FIXED
• Product: Gentoo Security

[Description Robert Buchholz (RETIRED) 2007-09-17 16:52:27 UTC]

libsndfile-1.0.17 does not check the size of decoded PCM data coming from the FLAC library in flac_buffer_copy() and writes it to a previously allocated buffer on the heap.
When seeking through a FLAC file with variable blocksize, a buffer with the current blocksize is allocated and reused with a block of possibly greater size.

Since the PCM stream is decoded from a (lossless) FLAC, at most 24 bits of every 32 bit PCM sample is controllable by the file (eg, you can create 0x00414141 loops in memory). The buffer is allocated at minimum 16*4 bytes while the technical maximum blocksize is 32768*4 bytes.

The issue was already known upstream and a change in libsndfile-1.0.18pre17 addressed it, but does not fix it robustly. I'll attach a fix for 1.0.17 (including our FLAC patches) in a moment. Besides the the changes in the development version this is not public yet.

[Comment 1 Robert Buchholz (RETIRED) 2007-09-17 16:54:31 UTC]

Created attachment 131163 [details, diff]
libsndfile-1.0.17-flac-buffer-overflow.patch

Backported patch (not approved by upstream yet).

[Comment 2 Robert Buchholz (RETIRED) 2007-09-17 21:09:38 UTC]

Created attachment 131171 [details, diff]
libsndfile-1.0.17-flac-buffer-overflow.patch

Updated, upstream approved patch.

[Comment 3 Robert Buchholz (RETIRED) 2007-09-19 00:15:04 UTC]

Setting whiteboard and cc'ing maintainers.
aballier and drac, can you please test the patch and prepare an ebuild.
Please attach the ebuild to this bug and do not commit it to CVS yet.

[Comment 4 Alexis Ballier 2007-09-19 05:52:50 UTC]

Created attachment 131269 [details]
ebuild

--- libsndfile-1.0.17.ebuild    2007-08-20 13:17:45.000000000 +0200
+++ libsndfile-1.0.17-r1.ebuild 2007-09-19 07:25:04.000000000 +0200
@@ -31,6 +31,7 @@
 
        epatch "${WORKDIR}/${P}+flac-1.1.3.patch"
        epatch "${FILESDIR}/${P}-ogg.patch"
+       epatch "${FILESDIR}/${P}-flac-buffer-overflow.patch"
        eautoreconf
        epunt_cxx
 }


patch seems to work fine from my basic testing.

[Comment 5 Robert Buchholz (RETIRED) 2007-09-19 12:05:31 UTC]

Alexis, we decided not to keep this confidential. Please commit the the ebuild and patch.
Thanks!

[Comment 6 Sune Kloppenborg Jeppesen (RETIRED) 2007-09-19 12:25:14 UTC]

Opening at the request of reporter.

[14:15] <rbu> i'll grab some food. please unrestrict bug https://bugs.gentoo.org/192834 when you get back

[Comment 7 Alexis Ballier 2007-09-19 15:37:58 UTC]

(In reply to comment #5)
> Alexis, we decided not to keep this confidential. Please commit the the ebuild
> and patch.

done, I had forgot to set keywords to ~all in my attached ebuild, fixed that before comitting

[Comment 8 Robert Buchholz (RETIRED) 2007-09-19 15:52:47 UTC]

Arches, please test and mark stable libsndfile-1.0.17-r1.
Targets are: "alpha amd64 arm hppa ia64 mips ppc ppc64 sh sparc x86"

Also, degrading to C2 because the flac use flag is disabled by default.

[Comment 9 Jeroen Roovers (RETIRED) 2007-09-19 16:16:46 UTC]

Stable for HPPA.

[Comment 10 Robert Buchholz (RETIRED) 2007-09-19 17:21:05 UTC]

CVE assigned CVE-2007-4974 to this issue.

[Comment 11 Markus Meier 2007-09-19 19:22:12 UTC]

x86 stable

[Comment 12 Raúl Porcel (RETIRED) 2007-09-20 13:47:17 UTC]

alpha/ia64 stable

[Comment 13 Tobias Scherbaum (RETIRED) 2007-09-20 18:17:23 UTC]

ppc stable

[Comment 14 Robert Buchholz (RETIRED) 2007-09-20 18:46:30 UTC]

amd64 stable

[Comment 15 Brent Baude (RETIRED) 2007-09-20 20:46:12 UTC]

ppc64 stable

[Comment 16 Friedrich Oslage (RETIRED) 2007-09-28 19:19:27 UTC]

Created attachment 132116 [details]
emerge --info output

Tested media-libs/libsndfile-1.0.17-r1 (USE="alsa flac sqlite") on sparc.
No bugs found.

[Comment 17 Raúl Porcel (RETIRED) 2007-09-29 09:22:24 UTC]

sparc stable, thanks Friedrich

[Comment 18 Robert Buchholz (RETIRED) 2007-10-07 21:32:47 UTC]

GLSA 200710-04, thanks anyone.