While computing sgs in spi_map_buf(), the data type
used in min_t() for max_seg_size is 'unsigned int' where
as that of ctlr->max_dma_len is 'size_t'.
min_t(unsigned int,x,y) gives wrong results if one of x/y is
'size_t'
Consider the below examples on a 64-bit machine (ie size_t is
64-bits, and unsigned int is 32-bit).
case 1) min_t(unsigned int, 5, 0x100000001);
case 2) min_t(size_t, 5, 0x100000001);
Case 1 returns '1', where as case 2 returns '5'. As you can see
the result from case 1 is wrong.
This patch fixes the above issue by using the data type of the
parameters that are used in min_t with maximum data length.
Fixes: commit 1a4e53d2fc4f68aa ("spi: Fix invalid sgs value")
Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Suggested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
---
drivers/spi/spi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index d96082dc3340..fb2896cdb3ce 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1019,10 +1019,10 @@ int spi_map_buf(struct spi_controller *ctlr, struct device *dev,
int i, ret;
if (vmalloced_buf || kmap_buf) {
- desc_len = min_t(unsigned int, max_seg_size, PAGE_SIZE);
+ desc_len = min_t(unsigned long, max_seg_size, PAGE_SIZE);
sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
} else if (virt_addr_valid(buf)) {
- desc_len = min_t(unsigned int, max_seg_size, ctlr->max_dma_len);
+ desc_len = min_t(size_t, max_seg_size, ctlr->max_dma_len);
sgs = DIV_ROUND_UP(len, desc_len);
} else {
return -EINVAL;
--
2.17.1
