On 1/17/19 8:17 AM, Ilya Dryomov wrote:
> On Tue, Jan 15, 2019 at 8:41 PM Gustavo A. R. Silva
> <gustavo@xxxxxxxxxxxxxx> wrote:
>>
>> 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;
>> struct boo entry[];
>> };
>>
>> instance = kmalloc(sizeof(struct foo) + count * sizeof(struct boo), 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 code was detected with the help of Coccinelle.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
>> ---
>> net/ceph/osdmap.c | 5 ++---
>> 1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
>> index 98c0ff3d6441..48a31dc9161c 100644
>> --- a/net/ceph/osdmap.c
>> +++ b/net/ceph/osdmap.c
>> @@ -495,9 +495,8 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
>> / sizeof(struct crush_rule_step))
>> goto bad;
>> #endif
>> - r = c->rules[i] = kmalloc(sizeof(*r) +
>> - yes*sizeof(struct crush_rule_step),
>> - GFP_NOFS);
>> + r = kmalloc(struct_size(r, steps, yes), GFP_NOFS);
>> + c->rules[i] = r;
>> if (r == NULL)
>> goto badmem;
>> dout(" rule %d is at %p\n", i, r);
>
> Applied.
>
Thanks, Ilya.
--
Gustavo
