From eb8c1206d6b170d4e798a00db7432e023853da5c Mon Sep 17 00:00:00 2001 From: wiredfool Date: Sun, 1 Nov 2020 14:16:38 +0000 Subject: [PATCH] Fix CVE-2020-35654 - OOB Write in TiffDecode.c * In some circumstances with some versions of libtiff (4.1.0+), there could be a 4 byte out of bound write when decoding a YCbCr tiff. * The Pillow code dates to 6.0.0 * Found and reported through Tidelift reason:Fix CVE-2020-35654 - OOB Write in TiffDecode.c Conflict:NA Reference:https://github.com/python-pillow/Pillow/commit/eb8c1206d6b170d4e798a00db7432e023853da5c --- src/libImaging/TiffDecode.c | 266 ++++++++++++++++++---------- 1 files changed, 168 insertions(+), 98 deletions(-) diff -Naur a/src/libImaging/TiffDecode.c b/src/libImaging/TiffDecode.c --- a/src/libImaging/TiffDecode.c 2021-03-04 14:28:42.632000000 +0800 +++ b/src/libImaging/TiffDecode.c 2021-03-04 14:47:03.790000000 +0800 @@ -227,54 +227,182 @@ return 0; } -int ReadStrip(TIFF* tiff, UINT32 row, UINT32* buffer) { - uint16 photometric = 0; // init to not PHOTOMETRIC_YCBCR - TIFFGetField(tiff, TIFFTAG_PHOTOMETRIC, &photometric); - +int _decodeStripYCbCr(Imaging im, ImagingCodecState state, TIFF *tiff) { // To avoid dealing with YCbCr subsampling, let libtiff handle it - if (photometric == PHOTOMETRIC_YCBCR) { - TIFFRGBAImage img; - char emsg[1024] = ""; - UINT32 rows_per_strip, rows_to_read; - int ok; + // Use a TIFFRGBAImage wrapping the tiff image, and let libtiff handle + // all of the conversion. Metadata read from the TIFFRGBAImage could + // be different from the metadata that the base tiff returns. + + INT32 strip_row; + UINT8 *new_data; + UINT32 rows_per_strip, row_byte_size, rows_to_read; + int ret; + TIFFRGBAImage img; + char emsg[1024] = ""; + int ok; + + ret = TIFFGetFieldDefaulted(tiff, TIFFTAG_ROWSPERSTRIP, &rows_per_strip); + if (ret != 1) { + rows_per_strip = state->ysize; + } + TRACE(("RowsPerStrip: %u \n", rows_per_strip)); + if (!(TIFFRGBAImageOK(tiff, emsg) && TIFFRGBAImageBegin(&img, tiff, 0, emsg))) { + TRACE(("Decode error, msg: %s", emsg)); + state->errcode = IMAGING_CODEC_BROKEN; + TIFFClose(tiff); + return -1; + } - TIFFGetFieldDefaulted(tiff, TIFFTAG_ROWSPERSTRIP, &rows_per_strip); - if ((row % rows_per_strip) != 0) { - TRACE(("Row passed to ReadStrip() must be first in a strip.")); - return -1; - } + img.req_orientation = ORIENTATION_TOPLEFT; + img.col_offset = 0; - if (TIFFRGBAImageOK(tiff, emsg) && TIFFRGBAImageBegin(&img, tiff, 0, emsg)) { - TRACE(("Initialized RGBAImage\n")); + if (state->xsize != img.width || state->ysize != img.height) { + TRACE(("Inconsistent Image Error: %d =? %d, %d =? %d", + state->xsize, img.width, state->ysize, img.height)); + state->errcode = IMAGING_CODEC_BROKEN; + TIFFRGBAImageEnd(&img); + TIFFClose(tiff); + return -1; + } + + /* overflow check for row byte size */ + if (INT_MAX / 4 < img.width) { + state->errcode = IMAGING_CODEC_MEMORY; + TIFFRGBAImageEnd(&img); + TIFFClose(tiff); + return -1; + } + + // TiffRGBAImages are 32bits/pixel. + row_byte_size = img.width * 4; + + /* overflow check for realloc */ + if (INT_MAX / row_byte_size < rows_per_strip) { + state->errcode = IMAGING_CODEC_MEMORY; + TIFFRGBAImageEnd(&img); + TIFFClose(tiff); + return -1; + } + + state->bytes = rows_per_strip * row_byte_size; - img.req_orientation = ORIENTATION_TOPLEFT; - img.row_offset = row; - img.col_offset = 0; + TRACE(("StripSize: %d \n", state->bytes)); - rows_to_read = min(rows_per_strip, img.height - row); + /* realloc to fit whole strip */ + /* malloc check above */ + new_data = realloc (state->buffer, state->bytes); + if (!new_data) { + state->errcode = IMAGING_CODEC_MEMORY; + TIFFRGBAImageEnd(&img); + TIFFClose(tiff); + return -1; + } - TRACE(("rows to read: %d\n", rows_to_read)); - ok = TIFFRGBAImageGet(&img, buffer, img.width, rows_to_read); + state->buffer = new_data; + + for (; state->y < state->ysize; state->y += rows_per_strip) { + img.row_offset = state->y; + rows_to_read = min(rows_per_strip, img.height - state->y); + + if (TIFFRGBAImageGet(&img, (UINT32 *)state->buffer, img.width, rows_to_read) == -1) { + TRACE(("Decode Error, y: %d\n", state->y )); + state->errcode = IMAGING_CODEC_BROKEN; TIFFRGBAImageEnd(&img); - } else { - ok = 0; + TIFFClose(tiff); + return -1; } - if (ok == 0) { - TRACE(("Decode Error, row %d; msg: %s\n", row, emsg)); - return -1; + TRACE(("Decoded strip for row %d \n", state->y)); + + // iterate over each row in the strip and stuff data into image + for (strip_row = 0; strip_row < min((INT32) rows_per_strip, state->ysize - state->y); strip_row++) { + TRACE(("Writing data into line %d ; \n", state->y + strip_row)); + + // UINT8 * bbb = state->buffer + strip_row * (state->bytes / rows_per_strip); + // TRACE(("chars: %x %x %x %x\n", ((UINT8 *)bbb)[0], ((UINT8 *)bbb)[1], ((UINT8 *)bbb)[2], ((UINT8 *)bbb)[3])); + + state->shuffle((UINT8*) im->image[state->y + state->yoff + strip_row] + + state->xoff * im->pixelsize, + state->buffer + strip_row * row_byte_size, + state->xsize); } + } + TIFFRGBAImageEnd(&img); + return 0; +} + +int _decodeStrip(Imaging im, ImagingCodecState state, TIFF *tiff) { + INT32 strip_row; + UINT8 *new_data; + UINT32 rows_per_strip, row_byte_size; + int ret; + + ret = TIFFGetField(tiff, TIFFTAG_ROWSPERSTRIP, &rows_per_strip); + if (ret != 1) { + rows_per_strip = state->ysize; + } + TRACE(("RowsPerStrip: %u \n", rows_per_strip)); - return 0; + // We could use TIFFStripSize, but for YCbCr data it returns subsampled data size + row_byte_size = (state->xsize * state->bits + 7) / 8; + + /* overflow check for realloc */ + if (INT_MAX / row_byte_size < rows_per_strip) { + state->errcode = IMAGING_CODEC_MEMORY; + TIFFClose(tiff); + return -1; + } + + state->bytes = rows_per_strip * row_byte_size; + + TRACE(("StripSize: %d \n", state->bytes)); + + if (TIFFStripSize(tiff) > state->bytes) { + // If the strip size as expected by LibTiff isn't what we're expecting, abort. + // man: TIFFStripSize returns the equivalent size for a strip of data as it would be returned in a + // call to TIFFReadEncodedStrip ... + + state->errcode = IMAGING_CODEC_MEMORY; + TIFFClose(tiff); + return -1; } - if (TIFFReadEncodedStrip(tiff, TIFFComputeStrip(tiff, row, 0), (tdata_t)buffer, -1) == -1) { - TRACE(("Decode Error, strip %d\n", TIFFComputeStrip(tiff, row, 0))); + /* realloc to fit whole strip */ + /* malloc check above */ + new_data = realloc (state->buffer, state->bytes); + if (!new_data) { + state->errcode = IMAGING_CODEC_MEMORY; + TIFFClose(tiff); return -1; } + state->buffer = new_data; + + for (; state->y < state->ysize; state->y += rows_per_strip) { + if (TIFFReadEncodedStrip(tiff, TIFFComputeStrip(tiff, state->y, 0), (tdata_t)state->buffer, -1) == -1) { + TRACE(("Decode Error, strip %d\n", TIFFComputeStrip(tiff, state->y, 0))); + state->errcode = IMAGING_CODEC_BROKEN; + TIFFClose(tiff); + return -1; + } + + TRACE(("Decoded strip for row %d \n", state->y)); + + // iterate over each row in the strip and stuff data into image + for (strip_row = 0; strip_row < min((INT32) rows_per_strip, state->ysize - state->y); strip_row++) { + TRACE(("Writing data into line %d ; \n", state->y + strip_row)); + + // UINT8 * bbb = state->buffer + strip_row * (state->bytes / rows_per_strip); + // TRACE(("chars: %x %x %x %x\n", ((UINT8 *)bbb)[0], ((UINT8 *)bbb)[1], ((UINT8 *)bbb)[2], ((UINT8 *)bbb)[3])); + + state->shuffle((UINT8*) im->image[state->y + state->yoff + strip_row] + + state->xoff * im->pixelsize, + state->buffer + strip_row * row_byte_size, + state->xsize); + } + } return 0; } @@ -283,6 +411,9 @@ char *filename = "tempfile.tif"; char *mode = "r"; TIFF *tiff; + uint16 photometric = 0; // init to not PHOTOMETRIC_YCBCR + int isYCbCr = 0; + int ret; /* buffer is the encoded file, bytes is the length of the encoded file */ /* it all ends up in state->buffer, which is a uint8* from Imaging.h */ @@ -343,6 +474,9 @@ } } + TIFFGetField(tiff, TIFFTAG_PHOTOMETRIC, &photometric); + isYCbCr = photometric == PHOTOMETRIC_YCBCR; + if (TIFFIsTiled(tiff)) { UINT32 x, y, tile_y, row_byte_size; UINT32 tile_width, tile_length, current_tile_width; @@ -411,75 +545,14 @@ } } } else { - UINT32 strip_row, row_byte_size; - UINT8 *new_data; - UINT32 rows_per_strip; - int ret; - - ret = TIFFGetField(tiff, TIFFTAG_ROWSPERSTRIP, &rows_per_strip); - if (ret != 1) { - rows_per_strip = state->ysize; + if (!isYCbCr) { + ret = _decodeStrip(im, state, tiff); } - TRACE(("RowsPerStrip: %u \n", rows_per_strip)); - // We could use TIFFStripSize, but for YCbCr data it returns subsampled data size - row_byte_size = (state->xsize * state->bits + 7) / 8; - - /* overflow check for realloc */ - if (INT_MAX / row_byte_size < rows_per_strip) { - state->errcode = IMAGING_CODEC_MEMORY; - TIFFClose(tiff); - return -1; - } - - state->bytes = rows_per_strip * row_byte_size; - - TRACE(("StripSize: %d \n", state->bytes)); - - if (TIFFStripSize(tiff) > state->bytes) { - // If the strip size as expected by LibTiff isn't what we're expecting, abort. - // man: TIFFStripSize returns the equivalent size for a strip of data as it would be returned in a - // call to TIFFReadEncodedStrip ... - - state->errcode = IMAGING_CODEC_MEMORY; - TIFFClose(tiff); - return -1; - } - - /* realloc to fit whole strip */ - /* malloc check above */ - new_data = realloc (state->buffer, state->bytes); - if (!new_data) { - state->errcode = IMAGING_CODEC_MEMORY; - TIFFClose(tiff); - return -1; - } - - state->buffer = new_data; - - for (; state->y < state->ysize; state->y += rows_per_strip) { - if (ReadStrip(tiff, state->y, (UINT32 *)state->buffer) == -1) { - TRACE(("Decode Error, strip %d\n", TIFFComputeStrip(tiff, state->y, 0))); - state->errcode = IMAGING_CODEC_BROKEN; - TIFFClose(tiff); - return -1; - } - - TRACE(("Decoded strip for row %d \n", state->y)); - - // iterate over each row in the strip and stuff data into image - for (strip_row = 0; strip_row < min(rows_per_strip, state->ysize - state->y); strip_row++) { - TRACE(("Writing data into line %d ; \n", state->y + strip_row)); - - // UINT8 * bbb = state->buffer + strip_row * (state->bytes / rows_per_strip); - // TRACE(("chars: %x %x %x %x\n", ((UINT8 *)bbb)[0], ((UINT8 *)bbb)[1], ((UINT8 *)bbb)[2], ((UINT8 *)bbb)[3])); - - state->shuffle((UINT8*) im->image[state->y + state->yoff + strip_row] + - state->xoff * im->pixelsize, - state->buffer + strip_row * row_byte_size, - state->xsize); - } + else { + ret = _decodeStripYCbCr(im, state, tiff); } + if (ret == -1) { return ret; } } TIFFClose(tiff);