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[slam] Avoid potential division by zero

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Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2016-01-27 23:27:47 +00:00
parent fef8e34b6f
commit 4ddd3d99c3
1 changed files with 13 additions and 7 deletions
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20
src/net/udp/slam.c
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@@ -415,6 +415,8 @@ static int slam_pull_value ( struct slam_request *slam,
static int slam_pull_header ( struct slam_request *slam, static int slam_pull_header ( struct slam_request *slam,
struct io_buffer *iobuf ) { struct io_buffer *iobuf ) {
void *header = iobuf->data; void *header = iobuf->data;
unsigned long total_bytes;
unsigned long block_size;
int rc; int rc;
/* If header matches cached header, just pull it and return */ /* If header matches cached header, just pull it and return */
@@ -431,22 +433,26 @@ static int slam_pull_header ( struct slam_request *slam,
*/ */
if ( ( rc = slam_pull_value ( slam, iobuf, NULL ) ) != 0 ) if ( ( rc = slam_pull_value ( slam, iobuf, NULL ) ) != 0 )
return rc; return rc;
if ( ( rc = slam_pull_value ( slam, iobuf, if ( ( rc = slam_pull_value ( slam, iobuf, &total_bytes ) ) != 0 )
&slam->total_bytes ) ) != 0 )
return rc; return rc;
if ( ( rc = slam_pull_value ( slam, iobuf, if ( ( rc = slam_pull_value ( slam, iobuf, &block_size ) ) != 0 )
&slam->block_size ) ) != 0 )
return rc; return rc;
/* Sanity check */
if ( block_size == 0 ) {
DBGC ( slam, "SLAM %p ignoring zero block size\n", slam );
return -EINVAL;
}
/* Update the cached header */ /* Update the cached header */
slam->header_len = ( iobuf->data - header ); slam->header_len = ( iobuf->data - header );
assert ( slam->header_len <= sizeof ( slam->header ) ); assert ( slam->header_len <= sizeof ( slam->header ) );
memcpy ( slam->header, header, slam->header_len ); memcpy ( slam->header, header, slam->header_len );
/* Calculate number of blocks */ /* Calculate number of blocks */
slam->num_blocks = ( ( slam->total_bytes + slam->block_size - 1 ) / slam->total_bytes = total_bytes;
slam->block_size ); slam->block_size = block_size;
slam->num_blocks = ( ( total_bytes + block_size - 1 ) / block_size );
DBGC ( slam, "SLAM %p has total bytes %ld, block size %ld, num " DBGC ( slam, "SLAM %p has total bytes %ld, block size %ld, num "
"blocks %ld\n", slam, slam->total_bytes, slam->block_size, "blocks %ld\n", slam, slam->total_bytes, slam->block_size,
slam->num_blocks ); slam->num_blocks );