From 9bc15dfba44533c9e0f2cc54eec519b359f7f0c5 Mon Sep 17 00:00:00 2001
From: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Date: Thu, 17 Nov 2016 00:04:57 +0100
Subject: [PATCH] ffmdec: sanitize codec parameters

A negative extradata size for example gets passed to memcpy in
avcodec_parameters_from_context causing a segmentation fault.

Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
---
 libavformat/ffmdec.c | 105 ++++++++++++++++++++++++++++++---------------------
 1 file changed, 62 insertions(+), 43 deletions(-)

diff --git a/libavformat/ffmdec.c b/libavformat/ffmdec.c
index 6b09be2..d5e10b0 100644
--- a/libavformat/ffmdec.c
+++ b/libavformat/ffmdec.c
@@ -21,6 +21,7 @@
 
 #include <stdint.h>
 
+#include "libavutil/imgutils.h"
 #include "libavutil/internal.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/intfloat.h"
@@ -28,6 +29,7 @@
 #include "libavutil/avassert.h"
 #include "libavutil/avstring.h"
 #include "libavutil/pixdesc.h"
+#include "libavcodec/internal.h"
 #include "avformat.h"
 #include "internal.h"
 #include "ffm.h"
@@ -277,6 +279,13 @@ static int ffm_append_recommended_configuration(AVStream *st, char **conf)
     return 0;
 }
 
+#define SANITIZE_PARAMETER(parameter, name, check, default) {                     \
+    if (check) {                                                                  \
+        av_log(codec, AV_LOG_WARNING, "Invalid " name " %d\n", codec->parameter); \
+        codec->parameter = default;                                               \
+    }                                                                             \
+}
+
 static int ffm2_read_header(AVFormatContext *s)
 {
     FFMContext *ffm = s->priv_data;
@@ -346,23 +355,29 @@ static int ffm2_read_header(AVFormatContext *s)
             }
             codec->codec_type = avio_r8(pb);
             if (codec->codec_type != codec_desc->type) {
-                av_log(s, AV_LOG_ERROR, "Codec type mismatch: expected %d, found %d\n",
+                av_log(s, AV_LOG_WARNING, "Codec type mismatch: expected %d, found %d\n",
                        codec_desc->type, codec->codec_type);
-                codec->codec_id = AV_CODEC_ID_NONE;
-                codec->codec_type = AVMEDIA_TYPE_UNKNOWN;
-                goto fail;
+                codec->codec_type = codec_desc->type;
             }
             codec->bit_rate = avio_rb32(pb);
+            if (codec->bit_rate < 0) {
+                av_log(codec, AV_LOG_WARNING, "Invalid bit rate %"PRId64"\n", codec->bit_rate);
+                codec->bit_rate = 0;
+            }
             codec->flags = avio_rb32(pb);
             codec->flags2 = avio_rb32(pb);
             codec->debug = avio_rb32(pb);
             if (codec->flags & AV_CODEC_FLAG_GLOBAL_HEADER) {
                 int size = avio_rb32(pb);
-                codec->extradata = av_mallocz(size + AV_INPUT_BUFFER_PADDING_SIZE);
-                if (!codec->extradata)
-                    return AVERROR(ENOMEM);
-                codec->extradata_size = size;
-                avio_read(pb, codec->extradata, size);
+                if (size < 0 || size >= FF_MAX_EXTRADATA_SIZE) {
+                    av_log(s, AV_LOG_WARNING, "Invalid extradata size %d\n", size);
+                } else {
+                    codec->extradata = av_mallocz(size + AV_INPUT_BUFFER_PADDING_SIZE);
+                    if (!codec->extradata)
+                        return AVERROR(ENOMEM);
+                    codec->extradata_size = size;
+                    avio_read(pb, codec->extradata, size);
+                }
             }
             break;
         case MKBETAG('S', 'T', 'V', 'I'):
@@ -372,21 +387,21 @@ static int ffm2_read_header(AVFormatContext *s)
             }
             codec->time_base.num = avio_rb32(pb);
             codec->time_base.den = avio_rb32(pb);
-            if (codec->time_base.num <= 0 || codec->time_base.den <= 0) {
-                av_log(s, AV_LOG_ERROR, "Invalid time base %d/%d\n",
+            if (codec->time_base.num < 0 || codec->time_base.den <= 0) {
+                av_log(s, AV_LOG_WARNING, "Invalid time base %d/%d\n",
                        codec->time_base.num, codec->time_base.den);
-                ret = AVERROR_INVALIDDATA;
-                goto fail;
+                codec->time_base.num = 0;
+                codec->time_base.den = 1;
             }
             codec->width = avio_rb16(pb);
             codec->height = avio_rb16(pb);
+            if (av_image_check_size(codec->width, codec->height, 0, s) < 0) {
+                codec->width = 0;
+                codec->height = 0;
+            }
             codec->gop_size = avio_rb16(pb);
             codec->pix_fmt = avio_rb32(pb);
-            if (!av_pix_fmt_desc_get(codec->pix_fmt)) {
-                av_log(s, AV_LOG_ERROR, "Invalid pix fmt id: %d\n", codec->pix_fmt);
-                codec->pix_fmt = AV_PIX_FMT_NONE;
-                goto fail;
-            }
+            SANITIZE_PARAMETER(pix_fmt, "pixel format", codec->pix_fmt != AV_PIX_FMT_NONE && !av_pix_fmt_desc_get(codec->pix_fmt), AV_PIX_FMT_NONE)
             codec->qmin = avio_r8(pb);
             codec->qmax = avio_r8(pb);
             codec->max_qdiff = avio_r8(pb);
@@ -432,13 +447,11 @@ static int ffm2_read_header(AVFormatContext *s)
                 goto fail;
             }
             codec->sample_rate = avio_rb32(pb);
-            if (codec->sample_rate <= 0) {
-                av_log(s, AV_LOG_ERROR, "Invalid sample rate %d\n", codec->sample_rate);
-                ret = AVERROR_INVALIDDATA;
-                goto fail;
-            }
+            SANITIZE_PARAMETER(sample_rate, "sample rate",        codec->sample_rate < 0, 0)
             codec->channels = avio_rl16(pb);
+            SANITIZE_PARAMETER(channels,    "number of channels", codec->channels < 0, 0)
             codec->frame_size = avio_rl16(pb);
+            SANITIZE_PARAMETER(frame_size,  "frame size",         codec->frame_size < 0, 0)
             break;
         case MKBETAG('C', 'P', 'R', 'V'):
             if (f_cprv++) {
@@ -563,13 +576,15 @@ static int ffm_read_header(AVFormatContext *s)
         }
         codec->codec_type = avio_r8(pb); /* codec_type */
         if (codec->codec_type != codec_desc->type) {
-            av_log(s, AV_LOG_ERROR, "Codec type mismatch: expected %d, found %d\n",
+            av_log(s, AV_LOG_WARNING, "Codec type mismatch: expected %d, found %d\n",
                    codec_desc->type, codec->codec_type);
-            codec->codec_id = AV_CODEC_ID_NONE;
-            codec->codec_type = AVMEDIA_TYPE_UNKNOWN;
-            goto fail;
+            codec->codec_type = codec_desc->type;
         }
         codec->bit_rate = avio_rb32(pb);
+        if (codec->bit_rate < 0) {
+            av_log(codec, AV_LOG_WARNING, "Invalid bit rate %"PRId64"\n", codec->bit_rate);
+            codec->bit_rate = 0;
+        }
         codec->flags = avio_rb32(pb);
         codec->flags2 = avio_rb32(pb);
         codec->debug = avio_rb32(pb);
@@ -579,19 +594,20 @@ static int ffm_read_header(AVFormatContext *s)
             codec->time_base.num = avio_rb32(pb);
             codec->time_base.den = avio_rb32(pb);
             if (codec->time_base.num <= 0 || codec->time_base.den <= 0) {
-                av_log(s, AV_LOG_ERROR, "Invalid time base %d/%d\n",
+                av_log(s, AV_LOG_WARNING, "Invalid time base %d/%d\n",
                        codec->time_base.num, codec->time_base.den);
-                goto fail;
+                codec->time_base.num = 0;
+                codec->time_base.den = 1;
             }
             codec->width = avio_rb16(pb);
             codec->height = avio_rb16(pb);
+            if (av_image_check_size(codec->width, codec->height, 0, s) < 0) {
+                codec->width = 0;
+                codec->height = 0;
+            }
             codec->gop_size = avio_rb16(pb);
             codec->pix_fmt = avio_rb32(pb);
-            if (!av_pix_fmt_desc_get(codec->pix_fmt)) {
-                av_log(s, AV_LOG_ERROR, "Invalid pix fmt id: %d\n", codec->pix_fmt);
-                codec->pix_fmt = AV_PIX_FMT_NONE;
-                goto fail;
-            }
+            SANITIZE_PARAMETER(pix_fmt, "pixel format", codec->pix_fmt != AV_PIX_FMT_NONE && !av_pix_fmt_desc_get(codec->pix_fmt), AV_PIX_FMT_NONE)
             codec->qmin = avio_r8(pb);
             codec->qmax = avio_r8(pb);
             codec->max_qdiff = avio_r8(pb);
@@ -633,23 +649,26 @@ static int ffm_read_header(AVFormatContext *s)
             break;
         case AVMEDIA_TYPE_AUDIO:
             codec->sample_rate = avio_rb32(pb);
-            if (codec->sample_rate <= 0) {
-                av_log(s, AV_LOG_ERROR, "Invalid sample rate %d\n", codec->sample_rate);
-                goto fail;
-            }
+            SANITIZE_PARAMETER(sample_rate, "sample rate",        codec->sample_rate < 0, 0)
             codec->channels = avio_rl16(pb);
+            SANITIZE_PARAMETER(channels,    "number of channels", codec->channels < 0, 0)
             codec->frame_size = avio_rl16(pb);
+            SANITIZE_PARAMETER(frame_size,  "frame size",         codec->frame_size < 0, 0)
             break;
         default:
             goto fail;
         }
         if (codec->flags & AV_CODEC_FLAG_GLOBAL_HEADER) {
             int size = avio_rb32(pb);
-            codec->extradata = av_mallocz(size + AV_INPUT_BUFFER_PADDING_SIZE);
-            if (!codec->extradata)
-                return AVERROR(ENOMEM);
-            codec->extradata_size = size;
-            avio_read(pb, codec->extradata, size);
+            if (size < 0 || size >= FF_MAX_EXTRADATA_SIZE) {
+                av_log(s, AV_LOG_WARNING, "Invalid extradata size %d\n", size);
+            } else {
+                codec->extradata = av_mallocz(size + AV_INPUT_BUFFER_PADDING_SIZE);
+                if (!codec->extradata)
+                    return AVERROR(ENOMEM);
+                codec->extradata_size = size;
+                avio_read(pb, codec->extradata, size);
+            }
         }
 
         avcodec_parameters_from_context(st->codecpar, codec);
-- 
2.10.2

