dma-contiguous: do not overwrite align in dma_alloc_contiguous()

BugLink: https://bugs.launchpad.net/bugs/1839395
The dma_alloc_contiguous() limits align at CONFIG_CMA_ALIGNMENT for
cma_alloc() however it does not restore it for the fallback routine.
This will result in a size mismatch between the allocation and free
when running into the fallback routines after cma_alloc() fails, if
the align is larger than CONFIG_CMA_ALIGNMENT.

This patch adds a cma_align to take care of cma_alloc() and prevent
the align from being overwritten.

Fixes: fdaeec198ada ("dma-contiguous: add dma_{alloc,free}_contiguous() helpers")
Reported-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
(cherry picked from commit c6622a425acd1d2f3a443cd39b490a8777b622d7)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Kleber Souza <kleber.souza@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index bfc0c17f2a3d411fcdee446f8aeeb0c1be0f681e..ea8259f53eda7124bb19c08562dd413b8d2f45e1 100644 (file)
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -243,8 +243,9 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
 
        /* CMA can be used only in the context which permits sleeping */
        if (cma && gfpflags_allow_blocking(gfp)) {
-               align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT);
-               page = cma_alloc(cma, count, align, gfp & __GFP_NOWARN);
+               size_t cma_align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT);
+
+               page = cma_alloc(cma, count, cma_align, gfp & __GFP_NOWARN);
        }
 
        /* Fallback allocation of normal pages */