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EncodeAlphaInternal: clear result->bw on error

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This avoids a double free should the function fail prior to
VP8BitWriterInit() and a previous trial result's buffer carried over.
Previously in ApplyFiltersAndEncode() trial.bw (with a previous
iteration's buffer) would be freed, followed by best.bw pointing to the
same buffer.

Since:
187d379d add a fallback to ALPHA_NO_COMPRESSION

In addition, check the return value of VP8BitWriterInit() in this
function.

Bug: webp:603
Change-Id: Ic258381ee26c8c16bc211d157c8153831c8c6910
This commit is contained in:
James Zern 2023-02-22 22:15:47 -08:00
parent 1347a32d82
commit a486d800b6
1 changed files with 3 additions and 1 deletions
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4
src/enc/alpha_enc.c
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@ -13,6 +13,7 @@
#include <assert.h> #include <assert.h>
#include <stdlib.h> #include <stdlib.h>
#include <string.h>
#include "src/enc/vp8i_enc.h" #include "src/enc/vp8i_enc.h"
#include "src/dsp/dsp.h" #include "src/dsp/dsp.h"
@ -148,6 +149,7 @@ static int EncodeAlphaInternal(const uint8_t* const data, int width, int height,
} }
} else { } else {
VP8LBitWriterWipeOut(&tmp_bw); VP8LBitWriterWipeOut(&tmp_bw);
memset(&result->bw, 0, sizeof(result->bw));
return 0; return 0;
} }
} }
@ -162,7 +164,7 @@ static int EncodeAlphaInternal(const uint8_t* const data, int width, int height,
header = method | (filter << 2); header = method | (filter << 2);
if (reduce_levels) header |= ALPHA_PREPROCESSED_LEVELS << 4; if (reduce_levels) header |= ALPHA_PREPROCESSED_LEVELS << 4;
VP8BitWriterInit(&result->bw, ALPHA_HEADER_LEN + output_size); if (!VP8BitWriterInit(&result->bw, ALPHA_HEADER_LEN + output_size)) ok = 0;
ok = ok && VP8BitWriterAppend(&result->bw, &header, ALPHA_HEADER_LEN); ok = ok && VP8BitWriterAppend(&result->bw, &header, ALPHA_HEADER_LEN);
ok = ok && VP8BitWriterAppend(&result->bw, output, output_size); ok = ok && VP8BitWriterAppend(&result->bw, output, output_size);