| From 783b3a6ff15ed6f82a8f8e6c8a6f3b84a9b04d4b Mon Sep 17 00:00:00 2001 |
| From: Kevin Backhouse <kevinbackhouse@github.com> |
| Date: Mon, 19 Apr 2021 18:06:00 +0100 |
| Subject: [PATCH] Improve bound checking in WebPImage::doWriteMetadata() |
| |
| --- |
| src/webpimage.cpp | 41 ++++++++++++++++++++++++++++++----------- |
| 1 file changed, 30 insertions(+), 11 deletions(-) |
| |
| diff --git a/src/webpimage.cpp b/src/webpimage.cpp |
| index 4ddec544c..fee110bca 100644 |
| --- a/src/webpimage.cpp |
| +++ b/src/webpimage.cpp |
| @@ -145,7 +145,7 @@ namespace Exiv2 { |
| DataBuf chunkId(WEBP_TAG_SIZE+1); |
| chunkId.pData_ [WEBP_TAG_SIZE] = '\0'; |
| |
| - io_->read(data, WEBP_TAG_SIZE * 3); |
| + readOrThrow(*io_, data, WEBP_TAG_SIZE * 3, Exiv2::kerCorruptedMetadata); |
| uint64_t filesize = Exiv2::getULong(data + WEBP_TAG_SIZE, littleEndian); |
| |
| /* Set up header */ |
| @@ -185,13 +185,20 @@ namespace Exiv2 { |
| case we have any exif or xmp data, also check |
| for any chunks with alpha frame/layer set */ |
| while ( !io_->eof() && (uint64_t) io_->tell() < filesize) { |
| - io_->read(chunkId.pData_, WEBP_TAG_SIZE); |
| - io_->read(size_buff, WEBP_TAG_SIZE); |
| - long size = Exiv2::getULong(size_buff, littleEndian); |
| + readOrThrow(*io_, chunkId.pData_, WEBP_TAG_SIZE, Exiv2::kerCorruptedMetadata); |
| + readOrThrow(*io_, size_buff, WEBP_TAG_SIZE, Exiv2::kerCorruptedMetadata); |
| + const uint32_t size_u32 = Exiv2::getULong(size_buff, littleEndian); |
| + |
| + // Check that `size_u32` is safe to cast to `long`. |
| + enforce(size_u32 <= static_cast<size_t>(std::numeric_limits<unsigned int>::max()), |
| + Exiv2::kerCorruptedMetadata); |
| + const long size = static_cast<long>(size_u32); |
| DataBuf payload(size); |
| - io_->read(payload.pData_, payload.size_); |
| - byte c; |
| - if ( payload.size_ % 2 ) io_->read(&c,1); |
| + readOrThrow(*io_, payload.pData_, payload.size_, Exiv2::kerCorruptedMetadata); |
| + if ( payload.size_ % 2 ) { |
| + byte c; |
| + readOrThrow(*io_, &c, 1, Exiv2::kerCorruptedMetadata); |
| + } |
| |
| /* Chunk with information about features |
| used in the file. */ |
| @@ -199,6 +206,7 @@ namespace Exiv2 { |
| has_vp8x = true; |
| } |
| if (equalsWebPTag(chunkId, WEBP_CHUNK_HEADER_VP8X) && !has_size) { |
| + enforce(size >= 10, Exiv2::kerCorruptedMetadata); |
| has_size = true; |
| byte size_buf[WEBP_TAG_SIZE]; |
| |
| @@ -227,6 +235,7 @@ namespace Exiv2 { |
| } |
| #endif |
| if (equalsWebPTag(chunkId, WEBP_CHUNK_HEADER_VP8) && !has_size) { |
| + enforce(size >= 10, Exiv2::kerCorruptedMetadata); |
| has_size = true; |
| byte size_buf[2]; |
| |
| @@ -244,11 +253,13 @@ namespace Exiv2 { |
| |
| /* Chunk with with lossless image data. */ |
| if (equalsWebPTag(chunkId, WEBP_CHUNK_HEADER_VP8L) && !has_alpha) { |
| + enforce(size >= 5, Exiv2::kerCorruptedMetadata); |
| if ((payload.pData_[4] & WEBP_VP8X_ALPHA_BIT) == WEBP_VP8X_ALPHA_BIT) { |
| has_alpha = true; |
| } |
| } |
| if (equalsWebPTag(chunkId, WEBP_CHUNK_HEADER_VP8L) && !has_size) { |
| + enforce(size >= 5, Exiv2::kerCorruptedMetadata); |
| has_size = true; |
| byte size_buf_w[2]; |
| byte size_buf_h[3]; |
| @@ -276,11 +287,13 @@ namespace Exiv2 { |
| |
| /* Chunk with animation frame. */ |
| if (equalsWebPTag(chunkId, WEBP_CHUNK_HEADER_ANMF) && !has_alpha) { |
| + enforce(size >= 6, Exiv2::kerCorruptedMetadata); |
| if ((payload.pData_[5] & 0x2) == 0x2) { |
| has_alpha = true; |
| } |
| } |
| if (equalsWebPTag(chunkId, WEBP_CHUNK_HEADER_ANMF) && !has_size) { |
| + enforce(size >= 12, Exiv2::kerCorruptedMetadata); |
| has_size = true; |
| byte size_buf[WEBP_TAG_SIZE]; |
| |
| @@ -309,16 +322,22 @@ namespace Exiv2 { |
| |
| io_->seek(12, BasicIo::beg); |
| while ( !io_->eof() && (uint64_t) io_->tell() < filesize) { |
| - io_->read(chunkId.pData_, 4); |
| - io_->read(size_buff, 4); |
| + readOrThrow(*io_, chunkId.pData_, 4, Exiv2::kerCorruptedMetadata); |
| + readOrThrow(*io_, size_buff, 4, Exiv2::kerCorruptedMetadata); |
| + |
| + const uint32_t size_u32 = Exiv2::getULong(size_buff, littleEndian); |
| |
| - long size = Exiv2::getULong(size_buff, littleEndian); |
| + // Check that `size_u32` is safe to cast to `long`. |
| + enforce(size_u32 <= static_cast<size_t>(std::numeric_limits<unsigned int>::max()), |
| + Exiv2::kerCorruptedMetadata); |
| + const long size = static_cast<long>(size_u32); |
| |
| DataBuf payload(size); |
| - io_->read(payload.pData_, size); |
| + readOrThrow(*io_, payload.pData_, size, Exiv2::kerCorruptedMetadata); |
| if ( io_->tell() % 2 ) io_->seek(+1,BasicIo::cur); // skip pad |
| |
| if (equalsWebPTag(chunkId, WEBP_CHUNK_HEADER_VP8X)) { |
| + enforce(size >= 1, Exiv2::kerCorruptedMetadata); |
| if (has_icc){ |
| payload.pData_[0] |= WEBP_VP8X_ICC_BIT; |
| } else { |