Commit f1f8f292 authored by Gustavo A. R. Silva's avatar Gustavo A. R. Silva Committed by Jens Axboe

block: bio: Use struct_size() in kmalloc()

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 bio_map_data {
        struct iovec iov[];

instance = kmalloc(sizeof(sizeof(struct bio_map_data) + sizeof(struct iovec) *
                          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, iov, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.
Reviewed-by: default avatarKees Cook <>
Signed-off-by: default avatarGustavo A. R. Silva <>
Signed-off-by: default avatarJens Axboe <>
parent 78b90a2c
......@@ -1120,8 +1120,7 @@ static struct bio_map_data *bio_alloc_map_data(struct iov_iter *data,
if (data->nr_segs > UIO_MAXIOV)
return NULL;
bmd = kmalloc(sizeof(struct bio_map_data) +
sizeof(struct iovec) * data->nr_segs, gfp_mask);
bmd = kmalloc(struct_size(bmd, iov, data->nr_segs), gfp_mask);
if (!bmd)
return NULL;
memcpy(bmd->iov, data->iov, sizeof(struct iovec) * data->nr_segs);
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