treewide: Use struct_size() for kmalloc()-family

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct foo {
    int stuff;
    void *entry[];
};

instance = kmalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);

This patch makes the changes for kmalloc()-family (and kvmalloc()-family)
uses. It was done via automatic conversion with manual review for the
"CHECKME" non-standard cases noted below, using the following Coccinelle
script:

// pkey_cache = kmalloc(sizeof *pkey_cache + tprops->pkey_tbl_len *
//                      sizeof *pkey_cache->table, GFP_KERNEL);
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@

- alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT), GFP)
+ alloc(struct_size(VAR, ELEMENT, COUNT), GFP)

// mr = kzalloc(sizeof(*mr) + m * sizeof(mr->map[0]), GFP_KERNEL);
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@

- alloc(sizeof(*VAR) + COUNT * sizeof(VAR->ELEMENT[0]), GFP)
+ alloc(struct_size(VAR, ELEMENT, COUNT), GFP)

// Same pattern, but can't trivially locate the trailing element name,
// or variable name.
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
expression SOMETHING, COUNT, ELEMENT;
@@

- alloc(sizeof(SOMETHING) + COUNT * sizeof(ELEMENT), GFP)
+ alloc(CHECKME_struct_size(&SOMETHING, ELEMENT, COUNT), GFP)

Signed-off-by: Kees Cook <keescook@chromium.org>

5 files changed, 8 insertions, 11 deletions

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 85ea92fcea540..9bc722ca83299 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -1074,8 +1074,7 @@ static struct dma_async_tx_descriptor *edma_prep_slave_sg(
 		return NULL;
 	}
 
-	edesc = kzalloc(sizeof(*edesc) + sg_len * sizeof(edesc->pset[0]),
-			GFP_ATOMIC);
+	edesc = kzalloc(struct_size(edesc, pset, sg_len), GFP_ATOMIC);
 	if (!edesc)
 		return NULL;
 
@@ -1192,8 +1191,7 @@ static struct dma_async_tx_descriptor *edma_prep_dma_memcpy(
 			nslots = 2;
 	}
 
-	edesc = kzalloc(sizeof(*edesc) + nslots * sizeof(edesc->pset[0]),
-			GFP_ATOMIC);
+	edesc = kzalloc(struct_size(edesc, pset, nslots), GFP_ATOMIC);
 	if (!edesc)
 		return NULL;
 
@@ -1315,8 +1313,7 @@ static struct dma_async_tx_descriptor *edma_prep_dma_cyclic(
 		}
 	}
 
-	edesc = kzalloc(sizeof(*edesc) + nslots * sizeof(edesc->pset[0]),
-			GFP_ATOMIC);
+	edesc = kzalloc(struct_size(edesc, pset, nslots), GFP_ATOMIC);
 	if (!edesc)
 		return NULL;
 
diff --git a/drivers/dma/moxart-dma.c b/drivers/dma/moxart-dma.c
index e1a5c2242f6fb..e04499c1f27f4 100644
--- a/drivers/dma/moxart-dma.c
+++ b/drivers/dma/moxart-dma.c
@@ -309,7 +309,7 @@ static struct dma_async_tx_descriptor *moxart_prep_slave_sg(
 		return NULL;
 	}
 
-	d = kzalloc(sizeof(*d) + sg_len * sizeof(d->sg[0]), GFP_ATOMIC);
+	d = kzalloc(struct_size(d, sg, sg_len), GFP_ATOMIC);
 	if (!d)
 		return NULL;
 
diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c
index d21c19822feb9..9483000fcf79a 100644
--- a/drivers/dma/omap-dma.c
+++ b/drivers/dma/omap-dma.c
@@ -917,7 +917,7 @@ static struct dma_async_tx_descriptor *omap_dma_prep_slave_sg(
 	}
 
 	/* Now allocate and setup the descriptor. */
-	d = kzalloc(sizeof(*d) + sglen * sizeof(d->sg[0]), GFP_ATOMIC);
+	d = kzalloc(struct_size(d, sg, sglen), GFP_ATOMIC);
 	if (!d)
 		return NULL;
 
diff --git a/drivers/dma/sa11x0-dma.c b/drivers/dma/sa11x0-dma.c
index c7a89c22890e5..b31d07c7d93c1 100644
--- a/drivers/dma/sa11x0-dma.c
+++ b/drivers/dma/sa11x0-dma.c
@@ -557,7 +557,7 @@ static struct dma_async_tx_descriptor *sa11x0_dma_prep_slave_sg(
 		}
 	}
 
-	txd = kzalloc(sizeof(*txd) + j * sizeof(txd->sg[0]), GFP_ATOMIC);
+	txd = kzalloc(struct_size(txd, sg, j), GFP_ATOMIC);
 	if (!txd) {
 		dev_dbg(chan->device->dev, "vchan %p: kzalloc failed\n", &c->vc);
 		return NULL;
@@ -627,7 +627,7 @@ static struct dma_async_tx_descriptor *sa11x0_dma_prep_dma_cyclic(
 	if (sglen == 0)
 		return NULL;
 
-	txd = kzalloc(sizeof(*txd) + sglen * sizeof(txd->sg[0]), GFP_ATOMIC);
+	txd = kzalloc(struct_size(txd, sg, sglen), GFP_ATOMIC);
 	if (!txd) {
 		dev_dbg(chan->device->dev, "vchan %p: kzalloc failed\n", &c->vc);
 		return NULL;
diff --git a/drivers/dma/sh/usb-dmac.c b/drivers/dma/sh/usb-dmac.c
index 31a145154e9f2..1bb1a8e09025f 100644
--- a/drivers/dma/sh/usb-dmac.c
+++ b/drivers/dma/sh/usb-dmac.c
@@ -269,7 +269,7 @@ static int usb_dmac_desc_alloc(struct usb_dmac_chan *chan, unsigned int sg_len,
 	struct usb_dmac_desc *desc;
 	unsigned long flags;
 
-	desc = kzalloc(sizeof(*desc) + sg_len * sizeof(desc->sg[0]), gfp);
+	desc = kzalloc(struct_size(desc, sg, sg_len), gfp);
 	if (!desc)
 		return -ENOMEM;