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spi: Fix erroneous sgs value with min_t()

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[ Upstream commit ebc4cb43ea5ada3db46c80156fca58a54b9bbca8 ]

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 <[email protected]>
Suggested-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: Biju Das <[email protected]>
Reviewed-by: Lad Prabhakar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
This commit is contained in:
Biju Das 2022-03-16 17:53:17 +00:00 • committed by Greg Kroah-Hartman
commit 0cdb512da0
1 changed files with 2 additions and 2 deletions
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4
drivers/spi/spi.c
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@ -844,10 +844,10 @@ 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;