Subject: Re: [PATCH] Fix allocation sizes of knfsd raparm hash

From: Takashi Iwai <[email-masked]>
Date: Sat, 16 Aug 2008 10:45:56 +0200

At Fri, 15 Aug 2008 15:02:21 -0400,
J. Bruce Fields wrote:
> 
> On Fri, Aug 15, 2008 at 03:34:39PM +0200, Takashi Iwai wrote:
> > The raparm was allocated in a wrong size in the commit
> > 
> >    ca80290ebda9009aedc4bd93ede5d397cb1853dc
> >    nfsd: permit unauthenticated stat of export root
> > 
> > and thus it resulted in memory corruption, eventually Oopsing.
> > This patch fixes the allocation size.
> 
> Whoops, my fault, now fixed; thanks!
> 
> (Out of curiosity--how did you find this?)

Actually I hit the related Oops with the latest linux-next tree.
Since this bug appears first on that tree and didn't occur on the
previous tree, it was apparently a regression.  So, I looked through
changes over knfsd since the previous tree, found a suspicious one,
and tried to fix.

The linux-next tree is pretty helpful to catch a regression if one
eats own dog foods everyday.

BTW, I've been building linux-next SUSE kernel packages at every
linux-next release.  The packages are found in the following URL:

    http://ftp.suse.com/pub/people/tiwai/kernel-next/

If anyone has a SUSE system and would like to try linux-next kernel,
just installs the package in addition.  It won't conflict with
existing standard kernel packages.

thanks,

Takashi

> 
> --b.
> 
> > 
> > Signed-off-by: Takashi Iwai <[email-masked]>
> > 
> > ---
> > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> > index bfa5453..30d606f 100644
> > --- a/fs/nfsd/vfs.c
> > +++ b/fs/nfsd/vfs.c
> > @@ -2093,7 +2093,7 @@ nfsd_racache_init(int cache_size)
> >  
> >  		raparm = &raparm_hash[i].pb_head;
> >  		for (j = 0; j < nperbucket; j++) {
> > -			*raparm = kzalloc(sizeof(*raparm), GFP_KERNEL);
> > +			*raparm = kzalloc(sizeof(**raparm), GFP_KERNEL);
> >  			if (!*raparm)
> >  				goto out_nomem;
> >  			raparm = &(*raparm)->p_next;
>