dm stripe: use struct_size() in kmalloc() (8adeac3b) · Commits · 戴 / test

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 stripe_c { ... struct stripe stripe[0]; }; In this case alloc_context() and dm_array_too_big() are removed and replaced by the direct use of the struct_size() helper in kmalloc(). Notice that open-coded form is prone to type mistakes. This code was detected with the help of Coccinelle. Signed-off-by:

Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by:

Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-stripe.c

+1 −14

Original line number	Diff line number	Diff line
		@@ -55,19 +55,6 @@ static void trigger_event(struct work_struct *work)
		dm_table_event(sc->ti->table);
		}

		static inline struct stripe_c *alloc_context(unsigned int stripes)
		{
		size_t len;

		if (dm_array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
		stripes))
		return NULL;

		len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);

		return kmalloc(len, GFP_KERNEL);
		}

		/*
		* Parse a single <dev> <sector> pair
		*/
		@@ -142,7 +129,7 @@ static int stripe_ctr(struct dm_target ti, unsigned int argc, char *argv)
		return -EINVAL;
		}

		sc = alloc_context(stripes);
		sc = kmalloc(struct_size(sc, stripe, stripes), GFP_KERNEL);
		if (!sc) {
		ti->error = "Memory allocation for striped context "
		"failed";

include/linux/device-mapper.h

+0 −3

Original line number	Diff line number	Diff line
		@@ -594,9 +594,6 @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
		*/
		#define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))

		#define dm_array_too_big(fixed, obj, num) \
		((num) > (UINT_MAX - (fixed)) / (obj))

		/*
		* Sector offset taken relative to the start of the target instead of
		* relative to the start of the device.

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