[SCSI] st: fix memory leak with >1MB tape I/O

There is a memory leak in the st driver when sending large enough reads or writes using st's direct I/O path. As part of mapping the application's memory, a buffer to hold page pointers is allocated and the count of mapped pages is stored in field do_dio. A non-zero do_dio marks that direct I/O is in use. But do_dio is only 1 byte in size. Mapping 256 4k pages overflows do_dio and causes it to be set to 0, like direct I/O option was not used. When the I/O completes, the buffer to hold the page pointers is not freed, and the page counts of the mapped pages are not reduced. Every I/O of this size then leaks memory. The size of do_dio needs to be increased to prevent it wrapping around. Signed-off-by: David Jeffery <djeffery@redhat.com> Acked-by: Kai Mäkisara <kai.makisara@kolumbus.fi> Signed-off-by: James Bottomley <JBottomley@Parallels.com>

[SCSI] st: fix memory leak with >1MB tape I/O
There is a memory leak in the st driver when sending large enough reads or writes using st's direct I/O path. As part of mapping the application's memory, a buffer to hold page pointers is allocated and the count of mapped pages is stored in field do_dio. A non-zero do_dio marks that direct I/O is in use. But do_dio is only 1 byte in size. Mapping 256 4k pages overflows do_dio and causes it to be set to 0, like direct I/O option was not used. When the I/O completes, the buffer to hold the page pointers is not freed, and the page counts of the mapped pages are not reduced. Every I/O of this size then leaks memory. The size of do_dio needs to be increased to prevent it wrapping around. Signed-off-by: David Jeffery <djeffery@redhat.com> Acked-by: Kai Mäkisara <kai.makisara@kolumbus.fi> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
David Jeffery · James Bottomley
1 parent ad07b4a896
Showing 1 changed file with 1 additions and 1 deletions Side-by-side Diff
drivers/scsi/st.h
@@ -35,8 +35,8 @@
 /* The tape buffer descriptor. */
 struct st_buffer {
 	unsigned char dma;	/* DMA-able buffer */
-	unsigned char do_dio;   /* direct i/o set up? */
 	unsigned char cleared;  /* internal buffer cleared after open? */
+	unsigned short do_dio;  /* direct i/o set up? */
 	int buffer_size;
 	int buffer_blocks;
 	int buffer_bytes;
...	...	@@ -35,8 +35,8 @@
35	35	/* The tape buffer descriptor. */
36	36	struct st_buffer {
37	37	unsigned char dma; /* DMA-able buffer */
38		- unsigned char do_dio; /* direct i/o set up? */
39	38	unsigned char cleared; /* internal buffer cleared after open? */
	39	+ unsigned short do_dio; /* direct i/o set up? */
40	40	int buffer_size;
41	41	int buffer_blocks;
42	42	int buffer_bytes;