[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v2 5/5] libxenguest: simplify kernel decompression
In all cases the kernel build makes available the uncompressed size in the final 4 bytes of the bzImage payload. Utilize this to avoid repeated realloc()ing of the output buffer. As a side effect this also addresses the previous mistaken return of 0 (success) from xc_try_{bzip2,lzma,xz}_decode() in case xc_dom_register_external() would have failed. As another side effect this also addresses the first error path of _xc_try_lzma_decode() previously bypassing lzma_end(). Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> --- v2: New. --- a/tools/libs/guest/xg_dom_bzimageloader.c +++ b/tools/libs/guest/xg_dom_bzimageloader.c @@ -48,18 +48,16 @@ static int xc_try_bzip2_decode( bz_stream stream; int ret; char *out_buf; - char *tmp_buf; int retval = -1; - unsigned int outsize; - uint64_t total; + unsigned int insize, outsize; stream.bzalloc = NULL; stream.bzfree = NULL; stream.opaque = NULL; - if ( dom->kernel_size == 0) + if ( *size <= 8 ) { - DOMPRINTF("BZIP2: Input is 0 size"); + DOMPRINTF("BZIP2: insufficient input data"); return -1; } @@ -70,22 +68,25 @@ static int xc_try_bzip2_decode( return -1; } - /* sigh. We don't know up-front how much memory we are going to need - * for the output buffer. Allocate the output buffer to be equal - * the input buffer to start, and we'll realloc as needed. - */ - outsize = dom->kernel_size; + insize = *size - 4; + outsize = *(uint32_t *)(*blob + insize); /* - * stream.avail_in and outsize are unsigned int, while kernel_size + * stream.avail_in and insize are unsigned int, while *size * is a size_t. Check we aren't overflowing. */ - if ( outsize != dom->kernel_size ) + if ( insize + 4 != *size ) { DOMPRINTF("BZIP2: Input too large"); goto bzip2_cleanup; } + if ( xc_dom_kernel_check_size(dom, outsize) ) + { + DOMPRINTF("BZIP2: output too large"); + goto bzip2_cleanup; + } + out_buf = malloc(outsize); if ( out_buf == NULL ) { @@ -94,86 +95,45 @@ static int xc_try_bzip2_decode( } stream.next_in = dom->kernel_blob; - stream.avail_in = dom->kernel_size; + stream.avail_in = insize; stream.next_out = out_buf; - stream.avail_out = dom->kernel_size; + stream.avail_out = outsize; - for ( ; ; ) + ret = BZ2_bzDecompress(&stream); + if ( ret == BZ_STREAM_END ) + DOMPRINTF("BZIP2: Saw data stream end"); + else if ( ret != BZ_OK ) { - ret = BZ2_bzDecompress(&stream); - if ( ret == BZ_STREAM_END ) - { - DOMPRINTF("BZIP2: Saw data stream end"); - retval = 0; - break; - } - if ( ret != BZ_OK ) - { - DOMPRINTF("BZIP2: error %d", ret); - free(out_buf); - goto bzip2_cleanup; - } + DOMPRINTF("BZIP2: error %d", ret); + free(out_buf); + goto bzip2_cleanup; + } - if ( stream.avail_out == 0 ) - { - /* Protect against output buffer overflow */ - if ( outsize > UINT_MAX / 2 ) - { - DOMPRINTF("BZIP2: output buffer overflow"); - free(out_buf); - goto bzip2_cleanup; - } - - if ( xc_dom_kernel_check_size(dom, outsize * 2) ) - { - DOMPRINTF("BZIP2: output too large"); - free(out_buf); - goto bzip2_cleanup; - } - - tmp_buf = realloc(out_buf, outsize * 2); - if ( tmp_buf == NULL ) - { - DOMPRINTF("BZIP2: Failed to realloc memory"); - free(out_buf); - goto bzip2_cleanup; - } - out_buf = tmp_buf; - - stream.next_out = out_buf + outsize; - stream.avail_out = (outsize * 2) - outsize; - outsize *= 2; - } - else if ( stream.avail_in == 0 ) - { - /* - * If there is output buffer available then this indicates - * that BZ2_bzDecompress would like more input data to be - * provided. However our complete input buffer is in - * memory and provided upfront so if avail_in is zero this - * actually indicates a truncated input. - */ - DOMPRINTF("BZIP2: not enough input"); - free(out_buf); - goto bzip2_cleanup; - } + if ( stream.total_out_lo32 != outsize || stream.total_out_hi32 ) + { + DOMPRINTF("BZIP2: got 0x%x%08x bytes instead of 0x%09x", + stream.total_out_hi32, stream.total_out_lo32, outsize); + free(out_buf); + goto bzip2_cleanup; } - total = (((uint64_t)stream.total_out_hi32) << 32) | stream.total_out_lo32; + if ( stream.avail_in ) + DOMPRINTF("BZIP2: Warning: %#x unconsumed bytes", stream.avail_in); - if ( xc_dom_register_external(dom, out_buf, total) ) + if ( xc_dom_register_external(dom, out_buf, outsize) ) { DOMPRINTF("BZIP2: Error registering stream output"); free(out_buf); goto bzip2_cleanup; } - DOMPRINTF("%s: BZIP2 decompress OK, 0x%zx -> 0x%lx", - __FUNCTION__, *size, (long unsigned int) total); + DOMPRINTF("%s: BZIP2 decompress OK, 0x%zx -> 0x%x", + __FUNCTION__, *size, outsize); *blob = out_buf; - *size = total; + *size = outsize; + retval = 0; bzip2_cleanup: BZ2_bzDecompressEnd(&stream); @@ -205,22 +165,24 @@ static int _xc_try_lzma_decode( lzma_ret ret; lzma_action action = LZMA_RUN; unsigned char *out_buf; - unsigned char *tmp_buf; int retval = -1; - size_t outsize; - const char *msg; + size_t insize, outsize; - if ( dom->kernel_size == 0) + if ( *size < 8 ) { - DOMPRINTF("%s: Input is 0 size", what); - return -1; + DOMPRINTF("%s: insufficient input data", what); + goto lzma_cleanup; + } + + insize = *size - 4; + outsize = *(uint32_t *)(*blob + insize); + + if ( xc_dom_kernel_check_size(dom, outsize) ) + { + DOMPRINTF("%s: output too large", what); + goto lzma_cleanup; } - /* sigh. We don't know up-front how much memory we are going to need - * for the output buffer. Allocate the output buffer to be equal - * the input buffer to start, and we'll realloc as needed. - */ - outsize = dom->kernel_size; out_buf = malloc(outsize); if ( out_buf == NULL ) { @@ -229,92 +191,68 @@ static int _xc_try_lzma_decode( } stream->next_in = dom->kernel_blob; - stream->avail_in = dom->kernel_size; + stream->avail_in = insize; stream->next_out = out_buf; - stream->avail_out = dom->kernel_size; + stream->avail_out = outsize; - for ( ; ; ) + ret = lzma_code(stream, action); + if ( ret == LZMA_STREAM_END ) + DOMPRINTF("%s: Saw data stream end", what); + else if ( ret != LZMA_OK ) { - ret = lzma_code(stream, action); - if ( ret == LZMA_STREAM_END ) + const char *msg; + + switch ( ret ) { - DOMPRINTF("%s: Saw data stream end", what); - retval = 0; + case LZMA_MEM_ERROR: + msg = strerror(ENOMEM); break; - } - if ( ret != LZMA_OK ) - { - switch ( ret ) - { - case LZMA_MEM_ERROR: - msg = strerror(ENOMEM); - break; - case LZMA_MEMLIMIT_ERROR: - msg = "Memory usage limit reached"; - break; + case LZMA_MEMLIMIT_ERROR: + msg = "Memory usage limit reached"; + break; - case LZMA_FORMAT_ERROR: - msg = "File format not recognized"; - break; + case LZMA_FORMAT_ERROR: + msg = "File format not recognized"; + break; - case LZMA_OPTIONS_ERROR: - // FIXME: Better message? - msg = "Unsupported compression options"; - break; + case LZMA_OPTIONS_ERROR: + // FIXME: Better message? + msg = "Unsupported compression options"; + break; - case LZMA_DATA_ERROR: - msg = "File is corrupt"; - break; + case LZMA_DATA_ERROR: + msg = "File is corrupt"; + break; - case LZMA_BUF_ERROR: - msg = "Unexpected end of input"; - break; + case LZMA_BUF_ERROR: + msg = "Unexpected end of input"; + break; - default: - msg = "Internal program error (bug)"; - break; - } - DOMPRINTF("%s: %s decompression error: %s", - __FUNCTION__, what, msg); - free(out_buf); - goto lzma_cleanup; + default: + msg = "Internal program error (bug)"; + break; } - if ( stream->avail_out == 0 ) - { - /* Protect against output buffer overflow */ - if ( outsize > SIZE_MAX / 2 ) - { - DOMPRINTF("%s: output buffer overflow", what); - free(out_buf); - goto lzma_cleanup; - } - - if ( xc_dom_kernel_check_size(dom, outsize * 2) ) - { - DOMPRINTF("%s: output too large", what); - free(out_buf); - goto lzma_cleanup; - } - - tmp_buf = realloc(out_buf, outsize * 2); - if ( tmp_buf == NULL ) - { - DOMPRINTF("%s: Failed to realloc memory", what); - free(out_buf); - goto lzma_cleanup; - } - out_buf = tmp_buf; - - stream->next_out = out_buf + outsize; - stream->avail_out = (outsize * 2) - outsize; - outsize *= 2; - } + DOMPRINTF("%s: %s decompression error: %s", + __FUNCTION__, what, msg); + free(out_buf); + goto lzma_cleanup; + } + + if ( stream->total_out != outsize ) + { + DOMPRINTF("%s: got 0x%"PRIx64" bytes instead of 0x%zx", + what, stream->total_out, outsize); + free(out_buf); + goto lzma_cleanup; } - if ( xc_dom_register_external(dom, out_buf, stream->total_out) ) + if ( stream->avail_in ) + DOMPRINTF("%s: Warning: %#zx unconsumed bytes", what, stream->avail_in); + + if ( xc_dom_register_external(dom, out_buf, outsize) ) { DOMPRINTF("%s: Error registering stream output", what); free(out_buf); @@ -322,10 +260,11 @@ static int _xc_try_lzma_decode( } DOMPRINTF("%s: %s decompress OK, 0x%zx -> 0x%zx", - __FUNCTION__, what, *size, (size_t)stream->total_out); + __FUNCTION__, what, *size, outsize); *blob = out_buf; - *size = stream->total_out; + *size = outsize; + retval = 0; lzma_cleanup: lzma_end(stream); @@ -408,8 +347,8 @@ static int xc_try_lzo1x_decode( { int ret; const unsigned char *cur = dom->kernel_blob; - unsigned char *out_buf = NULL; - size_t left = dom->kernel_size, outsize; + unsigned char *out_buf; + size_t left = dom->kernel_size, outsize, outtot; const char *msg; unsigned version; static const unsigned char magic[] = { @@ -435,6 +374,15 @@ static int xc_try_lzo1x_decode( return -1; } + left -= 4; + outtot = *(uint32_t *)(*blob + left); + + if ( xc_dom_kernel_check_size(dom, outtot) ) + { + DOMPRINTF("LZO1x: output too large"); + return -1; + } + /* get version (2bytes), skip library version (2), * 'need to be extracted' version (2) and method (1) */ version = lzo_read_16(cur + 9); @@ -471,10 +419,16 @@ static int xc_try_lzo1x_decode( cur += ret; left -= ret; + out_buf = malloc(outtot); + if ( !out_buf ) + { + DOMPRINTF("LZO1x: failed to alloc memory"); + return -1; + } + for ( outsize = 0; ; ) { lzo_uint src_len, dst_len, out_len; - unsigned char *tmp_buf; msg = "Short input"; if ( left < 4 ) @@ -483,6 +437,13 @@ static int xc_try_lzo1x_decode( dst_len = lzo_read_32(cur); if ( !dst_len ) { + msg = "Unexpected output size"; + if ( outsize != outtot ) + break; + + if ( left != 4 ) + DOMPRINTF("LZO1x: Warning: %#zx unconsumed bytes", left - 4); + msg = "Error registering stream output"; if ( xc_dom_register_external(dom, out_buf, outsize) ) break; @@ -514,19 +475,9 @@ static int xc_try_lzo1x_decode( break; msg = "Output buffer overflow"; - if ( outsize > SIZE_MAX - dst_len ) - break; - - msg = "Decompressed image too large"; - if ( xc_dom_kernel_check_size(dom, outsize + dst_len) ) - break; - - msg = "Failed to (re)alloc memory"; - tmp_buf = realloc(out_buf, outsize + dst_len); - if ( tmp_buf == NULL ) + if ( dst_len > outtot - outsize ) break; - out_buf = tmp_buf; out_len = dst_len; ret = lzo1x_decompress_safe(cur, src_len,
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