Re: [PATCH] selinux: fix memory leak in sel_make_bools

[Danny Feng]

On 08/14/2009 02:55 AM, Paul Moore wrote:
> On Thursday 13 August 2009 04:26:16 am Xiaotian Feng wrote:
> > In sel_make_bools, kernel allocates memory for bool_pending_names[i]
> > with security_get_bools. So if we just free bool_pending_names, those
> > memories for bool_pending_names[i] will be leaked.
> >
> > This patch resolves dozens of following kmemleak report after resuming
> > from suspend:
> > unreferenced object 0xffff88022e4c7380 (size 32):
> >    comm "init", pid 1, jiffies 4294677173
> >    backtrace:
> >      [<ffffffff810f76b5>] create_object+0x1a2/0x2a9
> >      [<ffffffff810f78bb>] kmemleak_alloc+0x26/0x4b
> >      [<ffffffff810ef3eb>] __kmalloc+0x18f/0x1b8
> >      [<ffffffff811cd511>] security_get_bools+0xd7/0x16f
> >      [<ffffffff811c48c0>] sel_write_load+0x12e/0x62b
> >      [<ffffffff810f9a39>] vfs_write+0xae/0x10b
> >      [<ffffffff810f9b56>] sys_write+0x4a/0x6e
> >      [<ffffffff81011b82>] system_call_fastpath+0x16/0x1b
> >      [<ffffffffffffffff>] 0xffffffffffffffff
> >
> > Signed-off-by: Xiaotian Feng<dfeng@xxxxxxxxxx>
> > ---
> >   security/selinux/selinuxfs.c |    6 +++++-
> >   1 files changed, 5 insertions(+), 1 deletions(-)
> >
> > diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
> > index b4fc506..ab93472 100644
> > --- a/security/selinux/selinuxfs.c
> > +++ b/security/selinux/selinuxfs.c
> > @@ -979,7 +979,11 @@ static int sel_make_bools(void)
> >   	u32 sid;
> >
> >   	/* remove any existing files */
> > -	kfree(bool_pending_names);
> > +	if (bool_pending_names) {
> > +		for (i = 0; i<  bool_num; i++)
> > +			kfree(bool_pending_names[i]);
> > +		kfree(bool_pending_names);
> > +	}
> >   	kfree(bool_pending_values);
> >   	bool_pending_names = NULL;
> >   	bool_pending_values = NULL;
>
> Since the code seems to rely on 'bool_num' in other places to ensure we don't
> walk off the end of the array it is probably safe to omit the 'if
> (bool_pending_names) ...' conditional and just rely on the for loop to do the
> right thing.
Thanks for point out, I'll resend V2 patch :-)

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