lkml.org 
[lkml]   [2021]   [Sep]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] afs: Prefer struct_size over open coded arithmetic
Date
As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing. This could lead
to values wrapping around and a smaller allocation being made than the
caller was expecting. Using those allocations could lead to linear
overflows of heap memory and other misbehaviors.

So, use the struct_size() helper to do the arithmetic instead of the
argument "size + size * count" in the kzalloc() function.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments

Signed-off-by: Len Baker <len.baker@gmx.com>
---
fs/afs/security.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/afs/security.c b/fs/afs/security.c
index 3c7a8fc4f93f..7c6a63a30394 100644
--- a/fs/afs/security.c
+++ b/fs/afs/security.c
@@ -219,8 +219,7 @@ void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
* yet.
*/
size++;
- new = kzalloc(sizeof(struct afs_permits) +
- sizeof(struct afs_permit) * size, GFP_NOFS);
+ new = kzalloc(struct_size(new, permits, size), GFP_NOFS);
if (!new)
goto out_put;

--
2.25.1
\
 
 \ /
  Last update: 2021-09-19 11:47    [W:0.047 / U:0.680 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site