lkml.org 
[lkml]   [2018]   [Mar]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Subject[RFC] SHASH_DESC_ON_STACK macro
Date
Hi Herbert,

There is an ongoing effort to remove all VLAs from the code base [1] and
while working on that I came across the following macro at
include/crypto/hash.h:154:

#define SHASH_DESC_ON_STACK(shash, ctx) \
char __##shash##_desc[sizeof(struct shash_desc) + \
crypto_shash_descsize(ctx)] CRYPTO_MINALIGN_ATTR; \
struct shash_desc *shash = (struct shash_desc *)__##shash##_desc


Currently, this macro is being used in 46 different places.

I wonder how big can tfm->descsize can get?

Do you think it is feasible to replace the call to crypto_shash_descsize
with a constant value and get rid of 46 VLA warnings?

I have sent some patches to replace the use of this macro with dynamic
memory allocation instead, but it seems that this is not a suitable
solution for all cases due to performance issues.

[1] https://lkml.org/lkml/2018/3/7/621

I'd really appreciate any feedback.
Thanks
--
Gustavo

\
 
 \ /
  Last update: 2018-03-21 16:08    [W:0.081 / U:0.072 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site