Hello Michal,

On 20 December 2017 at 10:20, Michal Hocko [off-list ref] wrote:

On Tue 19-12-17 17:45:40, Michael Kerrisk wrote:

quoted

But, is
there a pressing reason to make the change? (Okay, I guess iterating
using *_STAT is nicer than parsing /proc/sysvipc/*.)

The reporter of this issue claims that "Reading /proc/sysvipc/shm is way
slower than executing the system call." I haven't checked that but I can
imagine that /proc/sysvipc/shm can take quite some time when there are
_many_ segments registered.

Yes, that makes sense.

So they would like to use the syscall but
the interacting parties do not have compatible permissions.

So, I don't think there is any security issue, since the same info is
available in /proc/sysvipc/*. The only question would be whether
change in the *_STAT behavior might surprise some applications into
behaving differently. I presume the chances of that are low, but if it
was a concert, one could add new shmctl/msgctl/semctl *_STAT_ALL (or
some such) operations that have the desired behavior.

Cheers,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/

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