Inotify memory leak

Inotify memory leak

[Vegard Nossum]

Hi,

Inotify does not clean up properly when it fails to create the file
descriptor. So it leaks kernel memory. Watch "slabtop" while running
this program:

#include <sys/inotify.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
        int fds[2];

        /* Circumvent max inotify instances limit */
        while (pipe(fds) != -1)
                ;

        while (1)
                inotify_init();

        return 0;
}

Specifically, the problem is in inotify_init1 where the group pointer is leaked:

        group = inotify_new_group(user, inotify_max_queued_events);
[...]
        ret = anon_inode_getfd("inotify", &inotify_fops, group,
                                  O_RDONLY | flags);
        if (ret >= 0)
                return ret;

        atomic_dec(&user->inotify_devs);
out_free_uid:
        free_uid(user);
        return ret;

I think it should be easily fixed by calling fsnotify_put_group() at
the right place.


Vegard

Re: Inotify memory leak

[Eric Paris]

On Wed, 2010-11-24 at 00:15 +0100, Vegard Nossum wrote:
> Hi,
> 
> Inotify does not clean up properly when it fails to create the file
> descriptor. So it leaks kernel memory. Watch "slabtop" while running
> this program:
> 
> #include <sys/inotify.h>
> #include <unistd.h>

potential patch at
http://git.infradead.org/users/eparis/notify.git/shortlog/refs/heads/for-next

Only compiled, not tested.  Will try to do that after dinner!

-Eric