Messages in this thread Patch in this message | | | From | Andrew Gabbasov <> | Subject | [PATCH] spi: Fix per-page mapping of unaligned vmalloc-ed buffer | Date | Thu, 25 Jun 2015 11:08:36 -0500 |
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spi_map_buf() processes mapping of vmalloc-ed buffers in a special way, making mapping of every page separately. However, if the buffer is not aligned to page boundary (e.g. sub-array in a vmalloc-ed array), it fills the scatter table with page-size unaligned pieces, that cross page boundaries. This is incorrect and can, for example, cause memory corruption and various crashes when working with ubifs on spi-nor chips.
Fix this by using proper scatter table size and intra-page buffer lengths, so that the whole buffer splits into separate scatter table entries on page boundaries.
Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com> --- drivers/spi/spi.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 50910d8..14016dc 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -477,7 +477,9 @@ static int spi_map_buf(struct spi_master *master, struct device *dev, { const bool vmalloced_buf = is_vmalloc_addr(buf); const int desc_len = vmalloced_buf ? PAGE_SIZE : master->max_dma_len; - const int sgs = DIV_ROUND_UP(len, desc_len); + const int sgs = DIV_ROUND_UP(vmalloced_buf ? + len + offset_in_page(buf) : len, + desc_len); struct page *vm_page; void *sg_buf; size_t min; @@ -488,9 +490,10 @@ static int spi_map_buf(struct spi_master *master, struct device *dev, return ret; for (i = 0; i < sgs; i++) { - min = min_t(size_t, len, desc_len); if (vmalloced_buf) { + min = min_t(size_t, + len, desc_len - offset_in_page(buf)); vm_page = vmalloc_to_page(buf); if (!vm_page) { sg_free_table(sgt); @@ -499,6 +502,7 @@ static int spi_map_buf(struct spi_master *master, struct device *dev, sg_set_page(&sgt->sgl[i], vm_page, min, offset_in_page(buf)); } else { + min = min_t(size_t, len, desc_len); sg_buf = buf; sg_set_buf(&sgt->sgl[i], sg_buf, min); } -- 2.1.0
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