Tejun Heo wrote:
Calling sg_init_one() with NULL buf causes oops on certain
configurations. Don't initialize sg in ata_exec_internal() if
DMA_NONE and make the function complain if @buf is NULL when dma_dir
isn't DMA_NONE. While at it, fix comment.
The problem is discovered and initial patch was submitted by Arnd
Bergmann.
Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
Cc: Arnd Bergmann <arnd.bergmann@xxxxxxxxxx>
---
Hello, Arnd Bergmann.
Thanks for spotting and fixing this but ata_exec_internal_nodma() is
almost identical to ata_do_simple_cmd() and ata_exec_internal() itself
needs fixing anyway. This patch just fixes ata_exec_internal(). I'll
follow up with conversion to ata_do_simple_cmd().
Thanks.
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 011c0a8..70e02e9 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1332,7 +1332,7 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
}
/**
- * ata_exec_internal_sg - execute libata internal command
+ * ata_exec_internal - execute libata internal command
* @dev: Device to which the command is sent
* @tf: Taskfile registers for the command and the result
* @cdb: CDB for packet command
@@ -1354,10 +1354,15 @@ unsigned ata_exec_internal(struct ata_device *dev,
int dma_dir, void *buf, unsigned int buflen)
{
struct scatterlist sg;
+ unsigned int n_elem = 0;
- sg_init_one(&sg, buf, buflen);
+ if (dma_dir != DMA_NONE) {
+ WARN_ON(!buf);
+ sg_init_one(&sg, buf, buflen);
+ n_elem++;
+ }
- return ata_exec_internal_sg(dev, tf, cdb, dma_dir, &sg, 1);
+ return ata_exec_internal_sg(dev, tf, cdb, dma_dir, &sg, n_elem);
ACK, if you conditionally replace "&sg" with NULL. That's the safer
choice, as it guarantees (via an oops) that the user will not be
touching sg, if dma_dir==DMA_NONE.
Jeff
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