From: Narpat Mali <[email protected]> libavcodec/pthread_frame.c in FFmpeg before 5.1.2, as used in VLC and other products, leaves stale hwaccel state in worker threads, which allows attackers to trigger a use-after-free and execute arbitrary code in some circumstances (e.g., hardware re-initialization upon a mid-video SPS change when Direct3D11 is used).
Signed-off-by: Narpat Mali <[email protected]> Signed-off-by: Steve Sakoman <[email protected]> --- .../ffmpeg/ffmpeg/CVE-2022-48434.patch | 130 ++++++++++++++++++ .../recipes-multimedia/ffmpeg/ffmpeg_5.0.1.bb | 3 +- 2 files changed, 132 insertions(+), 1 deletion(-) create mode 100644 meta/recipes-multimedia/ffmpeg/ffmpeg/CVE-2022-48434.patch diff --git a/meta/recipes-multimedia/ffmpeg/ffmpeg/CVE-2022-48434.patch b/meta/recipes-multimedia/ffmpeg/ffmpeg/CVE-2022-48434.patch new file mode 100644 index 0000000000..3cd374dc39 --- /dev/null +++ b/meta/recipes-multimedia/ffmpeg/ffmpeg/CVE-2022-48434.patch @@ -0,0 +1,130 @@ +From e40c964a0678908e2c756741343ed50d6a99ee12 Mon Sep 17 00:00:00 2001 +From: Anton Khirnov <[email protected]> +Date: Fri, 28 Apr 2023 11:45:30 +0000 +Subject: [PATCH] lavc/pthread_frame: avoid leaving stale hwaccel state in + worker threads + +This state is not refcounted, so make sure it always has a well-defined +owner. + +Remove the block added in 091341f, as +this commit also solves that issue in a more general way. + +CVE:CVE-2022-48434 + +Upstream-Status: Backport [https://github.com/FFmpeg/FFmpeg/commit/cc867f2c09d2b69cee8a0eccd62aff002cbbfe11] + +Signed-off-by: Narpat Mali <[email protected]> +--- + libavcodec/pthread_frame.c | 46 +++++++++++++++++++++++++++++--------- + 1 file changed, 35 insertions(+), 11 deletions(-) + +diff --git a/libavcodec/pthread_frame.c b/libavcodec/pthread_frame.c +index 85a6bc9..e40dced 100644 +--- a/libavcodec/pthread_frame.c ++++ b/libavcodec/pthread_frame.c +@@ -145,6 +145,12 @@ typedef struct FrameThreadContext { + * Set for the first N packets, where N is the number of threads. + * While it is set, ff_thread_en/decode_frame won't return any results. + */ ++ ++ /* hwaccel state is temporarily stored here in order to transfer its ownership ++ * to the next decoding thread without the need for extra synchronization */ ++ const AVHWAccel *stash_hwaccel; ++ void *stash_hwaccel_context; ++ void *stash_hwaccel_priv; + } FrameThreadContext; + + #if FF_API_THREAD_SAFE_CALLBACKS +@@ -229,9 +235,17 @@ FF_ENABLE_DEPRECATION_WARNINGS + ff_thread_finish_setup(avctx); + + if (p->hwaccel_serializing) { ++ /* wipe hwaccel state to avoid stale pointers lying around; ++ * the state was transferred to FrameThreadContext in ++ * ff_thread_finish_setup(), so nothing is leaked */ ++ avctx->hwaccel = NULL; ++ avctx->hwaccel_context = NULL; ++ avctx->internal->hwaccel_priv_data = NULL; ++ + p->hwaccel_serializing = 0; + pthread_mutex_unlock(&p->parent->hwaccel_mutex); + } ++ av_assert0(!avctx->hwaccel); + + if (p->async_serializing) { + p->async_serializing = 0; +@@ -294,14 +308,10 @@ static int update_context_from_thread(AVCodecContext *dst, AVCodecContext *src, + dst->color_range = src->color_range; + dst->chroma_sample_location = src->chroma_sample_location; + +- dst->hwaccel = src->hwaccel; +- dst->hwaccel_context = src->hwaccel_context; +- + dst->channels = src->channels; + dst->sample_rate = src->sample_rate; + dst->sample_fmt = src->sample_fmt; + dst->channel_layout = src->channel_layout; +- dst->internal->hwaccel_priv_data = src->internal->hwaccel_priv_data; + + if (!!dst->hw_frames_ctx != !!src->hw_frames_ctx || + (dst->hw_frames_ctx && dst->hw_frames_ctx->data != src->hw_frames_ctx->data)) { +@@ -442,6 +452,12 @@ static int submit_packet(PerThreadContext *p, AVCodecContext *user_avctx, + pthread_mutex_unlock(&p->mutex); + return err; + } ++ ++ /* transfer hwaccel state stashed from previous thread, if any */ ++ av_assert0(!p->avctx->hwaccel); ++ FFSWAP(const AVHWAccel*, p->avctx->hwaccel, fctx->stash_hwaccel); ++ FFSWAP(void*, p->avctx->hwaccel_context, fctx->stash_hwaccel_context); ++ FFSWAP(void*, p->avctx->internal->hwaccel_priv_data, fctx->stash_hwaccel_priv); + } + + av_packet_unref(p->avpkt); +@@ -647,6 +663,14 @@ void ff_thread_finish_setup(AVCodecContext *avctx) { + async_lock(p->parent); + } + ++ /* save hwaccel state for passing to the next thread; ++ * this is done here so that this worker thread can wipe its own hwaccel ++ * state after decoding, without requiring synchronization */ ++ av_assert0(!p->parent->stash_hwaccel); ++ p->parent->stash_hwaccel = avctx->hwaccel; ++ p->parent->stash_hwaccel_context = avctx->hwaccel_context; ++ p->parent->stash_hwaccel_priv = avctx->internal->hwaccel_priv_data; ++ + pthread_mutex_lock(&p->progress_mutex); + if(atomic_load(&p->state) == STATE_SETUP_FINISHED){ + av_log(avctx, AV_LOG_WARNING, "Multiple ff_thread_finish_setup() calls\n"); +@@ -700,13 +724,6 @@ void ff_frame_thread_free(AVCodecContext *avctx, int thread_count) + + park_frame_worker_threads(fctx, thread_count); + +- if (fctx->prev_thread && avctx->internal->hwaccel_priv_data != +- fctx->prev_thread->avctx->internal->hwaccel_priv_data) { +- if (update_context_from_thread(avctx, fctx->prev_thread->avctx, 1) < 0) { +- av_log(avctx, AV_LOG_ERROR, "Failed to update user thread.\n"); +- } +- } +- + if (fctx->prev_thread && fctx->prev_thread != fctx->threads) + if (update_context_from_thread(fctx->threads->avctx, fctx->prev_thread->avctx, 0) < 0) { + av_log(avctx, AV_LOG_ERROR, "Final thread update failed\n"); +@@ -760,6 +777,13 @@ void ff_frame_thread_free(AVCodecContext *avctx, int thread_count) + av_freep(&fctx->threads); + ff_pthread_free(fctx, thread_ctx_offsets); + ++ /* if we have stashed hwaccel state, move it to the user-facing context, ++ * so it will be freed in avcodec_close() */ ++ av_assert0(!avctx->hwaccel); ++ FFSWAP(const AVHWAccel*, avctx->hwaccel, fctx->stash_hwaccel); ++ FFSWAP(void*, avctx->hwaccel_context, fctx->stash_hwaccel_context); ++ FFSWAP(void*, avctx->internal->hwaccel_priv_data, fctx->stash_hwaccel_priv); ++ + av_freep(&avctx->internal->thread_ctx); + } + +-- +2.40.0 + diff --git a/meta/recipes-multimedia/ffmpeg/ffmpeg_5.0.1.bb b/meta/recipes-multimedia/ffmpeg/ffmpeg_5.0.1.bb index 4bcbda9976..6ece34fcfd 100644 --- a/meta/recipes-multimedia/ffmpeg/ffmpeg_5.0.1.bb +++ b/meta/recipes-multimedia/ffmpeg/ffmpeg_5.0.1.bb @@ -28,7 +28,8 @@ SRC_URI = "https://www.ffmpeg.org/releases/${BP}.tar.xz \ file://0001-avcodec-smcenc-stop-accessing-out-of-bounds-frame.patch \ file://0001-avcodec-vp3-Add-missing-check-for-av_malloc.patch \ file://0001-avformat-nutdec-Add-check-for-avformat_new_stream.patch \ - " + file://CVE-2022-48434.patch \ + " SRC_URI[sha256sum] = "ef2efae259ce80a240de48ec85ecb062cecca26e4352ffb3fda562c21a93007b" -- 2.34.1
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