lkml.org 
[lkml]   [2016]   [May]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH 3.12 69/76] net: fix infoleak in rtnetlink
From
From: Vegard Nossum <vegard.nossum@gmail.com>
Date: Fri, 20 May 2016 14:04:54 +0200

> Just out of curiosity, was this observed in practice? I could be
> wrong, but I was under the impression that using designated
> initializers would zero the rest of the struct, including padding.

I compiled testcases and found that the compiler does not zero out
padding when using designated initializers.

You can do the same.

For example, on sparc 32-bit, this code:

struct foo {
int a;
short b;
int c;
};

extern void foo(struct foo *);

void bar(void)
{
struct foo f = { .a = 1, .b = 2, .c = 3 };

foo(&f);
}

gives:

mov 1, %g1
st %g1, [%fp-12]
mov 2, %g1
sth %g1, [%fp-8]
mov 3, %g1
st %g1, [%fp-4]

It does not initialize the padding between 'b' and 'c'.

\
 
 \ /
  Last update: 2016-05-20 19:01    [W:0.126 / U:2.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site