Not really... it comes down to "implicit padding in kernel ABI structures is bad". They can easily become security holes.
Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
>On Mon, Feb 20, 2012 at 01:07, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
>> --- a/include/linux/sysinfo.h
>> +++ b/include/linux/sysinfo.h
>> @@ -1,22 +1,24 @@
>> #ifndef _LINUX_SYSINFO_H
>> #define _LINUX_SYSINFO_H
>>
>> +#include <linux/types.h>
>> +
>> #define SI_LOAD_SHIFT 16
>> struct sysinfo {
>> - long uptime; /* Seconds since boot */
>> - unsigned long loads[3]; /* 1, 5, and 15 minute load
>averages */
>> - unsigned long totalram; /* Total usable main memory
>size */
>> - unsigned long freeram; /* Available memory size */
>> - unsigned long sharedram; /* Amount of shared memory */
>> - unsigned long bufferram; /* Memory used by buffers */
>> - unsigned long totalswap; /* Total swap space size */
>> - unsigned long freeswap; /* swap space still available
>*/
>> - unsigned short procs; /* Number of current
>processes */
>> - unsigned short pad; /* explicit padding for m68k
>*/
>> - unsigned long totalhigh; /* Total high memory size */
>> - unsigned long freehigh; /* Available high memory size
>*/
>> - unsigned int mem_unit; /* Memory unit size in bytes
>*/
>> - char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding: libc5
>uses this.. */
>> + __kernel_long_t uptime; /* Seconds since boot */
>> + __kernel_ulong_t loads[3]; /* 1, 5, and 15 minute load
>averages */
>> + __kernel_ulong_t totalram; /* Total usable main memory
>size */
>> + __kernel_ulong_t freeram; /* Available memory size */
>> + __kernel_ulong_t sharedram; /* Amount of shared memory */
>> + __kernel_ulong_t bufferram; /* Memory used by buffers */
>> + __kernel_ulong_t totalswap; /* Total swap space size */
>> + __kernel_ulong_t freeswap; /* swap space still available
>*/
>> + __u16 procs; /* Number of current
>processes */
>> + __u16 pad; /* Explicit padding for m68k
>*/
>
>Fueling the discussion about natural vs. 4-byte alignment?
>
>> + __kernel_ulong_t totalhigh; /* Total high memory size */
>> + __kernel_ulong_t freehigh; /* Available high memory size
>*/
>> + __u32 mem_unit; /* Memory unit size in bytes
>*/
>> + char _f[20-2*sizeof(__kernel_ulong_t)-sizeof(__u32)]; /*
>Padding: libc5 uses this.. */
>> };
>
>Gr{oetje,eeting}s,
>
> Geert
>
>--
>Geert Uytterhoeven -- There's lots of Linux beyond ia32 --
>geert@xxxxxxxxxxxxxx
>
>In personal conversations with technical people, I call myself a
>hacker. But
>when I'm talking to journalists I just say "programmer" or something
>like that.
> -- Linus Torvalds
--
Sent from my mobile phone. Please excuse my brevity and lack of formatting.
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