diff options
Diffstat (limited to 'lib/lz4.c')
| -rw-r--r-- | lib/lz4.c | 39 |
1 files changed, 23 insertions, 16 deletions
@@ -1813,7 +1813,8 @@ LZ4_decompress_generic( if ((dict==usingExtDict) && (match < lowPrefix)) { if (unlikely(op+length > oend-LASTLITERALS)) { if (partialDecoding) { - length = MIN(length, (size_t)(oend-op)); /* reach end of buffer */ + DEBUGLOG(7, "partialDecoding: dictionary match, close to dstEnd"); + length = MIN(length, (size_t)(oend-op)); } else { goto _output_error; /* end-of-block condition violated */ } } @@ -1921,29 +1922,34 @@ LZ4_decompress_generic( || ((!endOnInput) && (cpy>oend-WILDCOPYLENGTH)) ) { /* We've either hit the input parsing restriction or the output parsing restriction. - * If we've hit the input parsing condition then this must be the last sequence. - * If we've hit the output parsing condition then we are either using partialDecoding - * or we've hit the output parsing condition. + * In the normal scenario, decoding a full block, it must be the last sequence, + * otherwise it's an error (invalid input or dimensions). + * In partialDecoding scenario, it's necessary to ensure there is no buffer overflow. */ if (partialDecoding) { /* Since we are partial decoding we may be in this block because of the output parsing * restriction, which is not valid since the output buffer is allowed to be undersized. */ assert(endOnInput); - /* If we're in this block because of the input parsing condition, then we must be on the - * last sequence (or invalid), so we must check that we exactly consume the input. + DEBUGLOG(7, "partialDecoding: copying literals, close to input or output end") + DEBUGLOG(7, "partialDecoding: literal length = %u", (unsigned)length); + DEBUGLOG(7, "partialDecoding: remaining space in dstBuffer : %i", (int)(oend - op)); + DEBUGLOG(7, "partialDecoding: remaining space in srcBuffer : %i", (int)(iend - ip)); + /* Finishing in the middle of a literals segment, + * due to lack of input. */ - if ((ip+length>iend-(2+1+LASTLITERALS)) && (ip+length != iend) && (cpy != oend)) { goto _output_error; } - assert(ip+length <= iend); - /* We are finishing in the middle of a literals segment. - * Break after the copy. + if (ip+length > iend) { + length = (size_t)(iend-ip); + cpy = op + length; + } + /* Finishing in the middle of a literals segment, + * due to lack of output space. */ if (cpy > oend) { cpy = oend; assert(op<=oend); length = (size_t)(oend-op); } - assert(ip+length <= iend); } else { /* We must be on the last sequence because of the parsing limitations so check * that we exactly regenerate the original size (must be exact when !endOnInput). @@ -1954,14 +1960,15 @@ LZ4_decompress_generic( */ if ((endOnInput) && ((ip+length != iend) || (cpy > oend))) { goto _output_error; } } - memmove(op, ip, length); /* supports overlapping memory regions, which only matters for in-place decompression scenarios */ + memmove(op, ip, length); /* supports overlapping memory regions; only matters for in-place decompression scenarios */ ip += length; op += length; - /* Necessarily EOF when !partialDecoding. When partialDecoding - * it is EOF if we've either filled the output buffer or hit - * the input parsing restriction. + /* Necessarily EOF when !partialDecoding. + * When partialDecoding, it is EOF if we've either + * filled the output buffer or + * can't proceed with reading an offset for following match. */ - if (!partialDecoding || (cpy == oend) || (ip == iend)) { + if (!partialDecoding || (cpy == oend) || (ip >= (iend-2))) { break; } } else { |