{"id":590,"date":"2016-09-21T17:21:10","date_gmt":"2016-09-21T15:21:10","guid":{"rendered":"http:\/\/blogs.gentoo.org\/ago\/?p=590"},"modified":"2016-11-03T18:09:44","modified_gmt":"2016-11-03T16:09:44","slug":"libav-divide-by-zero-in-sbr_make_f_master-aacsbr-c","status":"publish","type":"post","link":"https:\/\/blogs.gentoo.org\/ago\/2016\/09\/21\/libav-divide-by-zero-in-sbr_make_f_master-aacsbr-c\/","title":{"rendered":"libav: divide-by-zero in sbr_make_f_master (aacsbr.c)"},"content":{"rendered":"<p><strong>Description<\/strong>:<br \/>\n<a href=\"https:\/\/libav.org\/\">Libav<\/a> is an open source set of tools for audio and video processing.<\/p>\n<p>A fuzzing with an mp3 file as input discovered a divide-by-zero in sbr_make_f_master.<\/p>\n<p>The complete ASan output:<\/p>\n<pre><font size=\"2\"># avconv -i $FILE -f null -\r\navconv version 11.7, Copyright (c) 2000-2016 the Libav developers\r\n  built on Aug 16 2016 15:34:42 with clang version 3.8.1 (tags\/RELEASE_381\/final)\r\n[mpeg @ 0x61a00001f280] Format detected only with low score of 25, misdetection possible!\r\n[aac @ 0x619000000580] Sample rate index in program config element does not match the sample rate index configured by the container.\r\n[aac @ 0x619000000580] SBR was found before the first channel element.\r\nASAN:DEADLYSIGNAL\r\n=================================================================\r\n==29103==ERROR: AddressSanitizer: FPE on unknown address 0x7fbd80295491 (pc 0x7fbd80295491 bp 0x7ffde63eb2f0 sp 0x7ffde63eafa0 T0)\r\n    #0 0x7fbd80295490 in sbr_make_f_master \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/libavcodec\/aacsbr.c:338:57\r\n    #1 0x7fbd80295490 in sbr_reset \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/libavcodec\/aacsbr.c:1045\r\n    #2 0x7fbd80295490 in ff_decode_sbr_extension \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/libavcodec\/aacsbr.c:1093\r\n    #3 0x7fbd801efe1b in decode_extension_payload \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/libavcodec\/aacdec.c:2196:15\r\n    #4 0x7fbd801efe1b in aac_decode_frame_int \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/libavcodec\/aacdec.c:2866\r\n    #5 0x7fbd801d3bbb in aac_decode_frame \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/libavcodec\/aacdec.c:2959:15\r\n    #6 0x7fbd823ed42a in avcodec_decode_audio4 \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/libavcodec\/utils.c:1657:15\r\n    #7 0x7fbd83f00b20 in try_decode_frame \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/libavformat\/utils.c:1914:19\r\n    #8 0x7fbd83ef76e2 in avformat_find_stream_info \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/libavformat\/utils.c:2276:9\r\n    #9 0x50d195 in open_input_file \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/avconv_opt.c:726:11\r\n    #10 0x50b625 in open_files \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/avconv_opt.c:2127:15\r\n    #11 0x50af81 in avconv_parse_options \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/avconv_opt.c:2164:11\r\n    #12 0x541414 in main \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/avconv.c:2630:11\r\n    #13 0x7fbd7e77f61f in __libc_start_main \/var\/tmp\/portage\/sys-libs\/glibc-2.22-r4\/work\/glibc-2.22\/csu\/libc-start.c:289\r\n    #14 0x41d098 in _init (\/usr\/bin\/avconv+0x41d098)\r\n\r\nAddressSanitizer can not provide additional info.\r\nSUMMARY: AddressSanitizer: FPE \/var\/tmp\/portage\/media-video\/libav-11.7\/work\/libav-11.7\/libavcodec\/aacsbr.c:338:57 in sbr_make_f_master\r\n==29103==ABORTING\r\n<\/font><\/pre>\n<p><strong>Affected version:<\/strong><br \/>\n11.7<\/p>\n<p><strong>Fixed version:<\/strong><br \/>\nN\/A<\/p>\n<p><strong>Commit fix:<\/strong><br \/>\n<a href=\"https:\/\/git.libav.org\/?p=libav.git;a=blobdiff;f=libavcodec\/aacsbr.c;h=7d156e525b40b197c38db17acf16730845b91e56;hp=dbfb1677813ce6c531e4362d0be7ccf9fdfdd28e;hb=a50a5ff29ec5a8243499769e2bb9b5509ce9fd52;hpb=f55e3ff5891daf3d538b4d9176371960200d68fa\">https:\/\/git.libav.org\/?p=libav.git;a=blobdiff;f=libavcodec\/aacsbr.c;h=7d156e525b40b197c38db17acf16730845b91e56;hp=dbfb1677813ce6c531e4362d0be7ccf9fdfdd28e;hb=a50a5ff29ec5a8243499769e2bb9b5509ce9fd52;hpb=f55e3ff5891daf3d538b4d9176371960200d68fa<\/a><\/p>\n<p><strong>Credit:<\/strong><br \/>\nThis bug was discovered by Agostino Sarubbo of Gentoo.<\/p>\n<p><strong>CVE:<\/strong><br \/>\nCVE-2016-7499<\/p>\n<p><strong>Timeline:<\/strong><br \/>\n2016-08-15: bug discovered<br \/>\n2016-08-16: bug reported to upstream<br \/>\n2016-09-21: blog post about the issue<br \/>\n2016-09-21: CVE assigned<br \/>\n2016-11-02: upstream released a patch<\/p>\n<p><strong>Note:<\/strong><br \/>\nThis bug was found with <a href=\"http:\/\/lcamtuf.coredump.cx\/afl\">American Fuzzy Lop<\/a>.<\/p>\n<p><strong>Permalink:<\/strong><\/p>\n<blockquote data-secret=\"rBM8d3xvPB\" class=\"wp-embedded-content\"><p><a href=\"http:\/\/blogs.gentoo.org\/ago\/2016\/09\/21\/libav-divide-by-zero-in-sbr_make_f_master-aacsbr-c\/\">libav: divide-by-zero in sbr_make_f_master (aacsbr.c)<\/a><\/p><\/blockquote>\n<p><iframe class=\"wp-embedded-content\" sandbox=\"allow-scripts\" security=\"restricted\" style=\"position: absolute; clip: rect(1px, 1px, 1px, 1px);\" src=\"http:\/\/blogs.gentoo.org\/ago\/2016\/09\/21\/libav-divide-by-zero-in-sbr_make_f_master-aacsbr-c\/embed\/#?secret=rBM8d3xvPB\" data-secret=\"rBM8d3xvPB\" width=\"600\" height=\"338\" title=\"&#8220;libav: divide-by-zero in sbr_make_f_master (aacsbr.c)&#8221; &#8212; agostino&#039;s blog\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\" scrolling=\"no\"><\/iframe><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Description: Libav is an open source set of tools for audio and video processing. A fuzzing with an mp3 file as input discovered a divide-by-zero in sbr_make_f_master. The complete ASan output: # avconv -i $FILE -f null &#8211; avconv version &hellip; <a href=\"https:\/\/blogs.gentoo.org\/ago\/2016\/09\/21\/libav-divide-by-zero-in-sbr_make_f_master-aacsbr-c\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":140,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":"","jetpack_publicize_message":"","jetpack_is_tweetstorm":false,"jetpack_publicize_feature_enabled":true},"categories":[12,10],"tags":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2EaBc-9w","_links":{"self":[{"href":"https:\/\/blogs.gentoo.org\/ago\/wp-json\/wp\/v2\/posts\/590"}],"collection":[{"href":"https:\/\/blogs.gentoo.org\/ago\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.gentoo.org\/ago\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.gentoo.org\/ago\/wp-json\/wp\/v2\/users\/140"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.gentoo.org\/ago\/wp-json\/wp\/v2\/comments?post=590"}],"version-history":[{"count":4,"href":"https:\/\/blogs.gentoo.org\/ago\/wp-json\/wp\/v2\/posts\/590\/revisions"}],"predecessor-version":[{"id":832,"href":"https:\/\/blogs.gentoo.org\/ago\/wp-json\/wp\/v2\/posts\/590\/revisions\/832"}],"wp:attachment":[{"href":"https:\/\/blogs.gentoo.org\/ago\/wp-json\/wp\/v2\/media?parent=590"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.gentoo.org\/ago\/wp-json\/wp\/v2\/categories?post=590"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.gentoo.org\/ago\/wp-json\/wp\/v2\/tags?post=590"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}