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[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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