From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Gabbasov Subject: [PATCH] spi: Fix per-page mapping of unaligned vmalloc-ed buffer Date: Mon, 1 Jun 2015 05:14:36 -0500 Message-ID: <1433153676-18229-1-git-send-email-andrew_gabbasov@mentor.com> Mime-Version: 1.0 Content-Type: text/plain To: Return-path: Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: 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 --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html