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Add fbounds-safety annotations for WebPRescaler
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Reasoning: The `irow` and `frow` pointers in `WebPRescaler` (src/utils/rescaler_utils.h:49) were annotated with `WEBP_COUNTED_BY(dst_width * num_channels)`. This is based on their initialization in `WebPRescalerInit` (src/utils/rescaler_utils.c:82-83) where they are assigned parts of the `work` buffer, whose total size is `2 * dst_width * num_channels`. The `work` parameter in `WebPRescalerInit` (src/utils/rescaler_utils.h:58, src/utils/rescaler_utils.c:33) was also annotated accordingly. To satisfy the side-by-side assignment requirement for external bounds, assignments to `rescaler->irow` and `rescaler->frow` in `WebPRescalerInit` were moved closer to the assignments of `dst_width` and `num_channels` (src/utils/rescaler_utils.c:50-53). Since `work` have bound information, `WEBP_UNSAFE_MEMSET` has been changed to `memset`. In `WebPRescalerImport` (src/utils/rescaler_utils.c:140-150), where `irow` and `frow` are swapped, self-assignments for `dst_width` and `num_channels` were added side-by-side with the pointer assignments. Additionally, `WEBP_UNSAFE_FORGE_BIDI_INDEXABLE` was used for the pointer assignments to handle the `WEBP_ASSUME_UNSAFE_INDEXABLE_ABI` setting used during testing. Bug: 432511821 Change-Id: If716fb79a06dee9e807eff060806daf038810523
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@@ -30,7 +30,8 @@ WEBP_ASSUME_UNSAFE_INDEXABLE_ABI
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int WebPRescalerInit(WebPRescaler* const rescaler, int src_width,
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int src_height, uint8_t* const dst, int dst_width,
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int dst_height, int dst_stride, int num_channels,
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rescaler_t* const work) {
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rescaler_t* const WEBP_COUNTED_BY(2ULL * dst_width *
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num_channels) work) {
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const int x_add = src_width, x_sub = dst_width;
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const int y_add = src_height, y_sub = dst_height;
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const uint64_t total_size = 2ull * dst_width * num_channels * sizeof(*work);
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@@ -47,6 +48,9 @@ int WebPRescalerInit(WebPRescaler* const rescaler, int src_width,
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rescaler->dst = dst;
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rescaler->dst_stride = dst_stride;
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rescaler->num_channels = num_channels;
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rescaler->irow = work;
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rescaler->frow = work + num_channels * dst_width;
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memset(work, 0, (size_t)total_size);
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// for 'x_expand', we use bilinear interpolation
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rescaler->x_add = rescaler->x_expand ? (x_sub - 1) : x_add;
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@@ -79,9 +83,6 @@ int WebPRescalerInit(WebPRescaler* const rescaler, int src_width,
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rescaler->fy_scale = WEBP_RESCALER_FRAC(1, rescaler->x_add);
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// rescaler->fxy_scale is unused here.
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}
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rescaler->irow = work;
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rescaler->frow = work + num_channels * dst_width;
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WEBP_UNSAFE_MEMSET(work, 0, (size_t)total_size);
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WebPRescalerDspInit();
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return 1;
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@@ -136,7 +137,11 @@ int WebPRescalerImport(WebPRescaler* const rescaler, int num_lines,
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if (rescaler->y_expand) {
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rescaler_t* const tmp = rescaler->irow;
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rescaler->irow = rescaler->frow;
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rescaler->frow = tmp;
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rescaler->frow = WEBP_UNSAFE_FORGE_BIDI_INDEXABLE(
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rescaler_t*, tmp,
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rescaler->num_channels * rescaler->dst_width * sizeof(*tmp));
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WEBP_SELF_ASSIGN(rescaler->dst_width);
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WEBP_SELF_ASSIGN(rescaler->num_channels);
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}
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WebPRescalerImportRow(rescaler, src);
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if (!rescaler->y_expand) { // Accumulate the contribution of the new row.
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@@ -46,7 +46,9 @@ struct WebPRescaler {
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int src_y, dst_y; // row counters for input and output
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uint8_t* dst;
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int dst_stride;
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rescaler_t *irow, *frow; // work buffer
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// work buffer
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rescaler_t* WEBP_COUNTED_BY(dst_width* num_channels) irow;
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rescaler_t* WEBP_COUNTED_BY(dst_width* num_channels) frow;
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};
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// Initialize a rescaler given scratch area 'work' and dimensions of src & dst.
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@@ -54,7 +56,8 @@ struct WebPRescaler {
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int WebPRescalerInit(WebPRescaler* const rescaler, int src_width,
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int src_height, uint8_t* const dst, int dst_width,
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int dst_height, int dst_stride, int num_channels,
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rescaler_t* const work);
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rescaler_t* const WEBP_COUNTED_BY(2ULL * dst_width *
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num_channels) work);
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// If either 'scaled_width' or 'scaled_height' (but not both) is 0 the value
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// will be calculated preserving the aspect ratio, otherwise the values are
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