[U-Boot] [PATCH 1/1] ubifs: avoid possible NULL dereference

[Ladislav Michl]

On Tue, Nov 21, 2017 at 10:16:40PM +0100, Wolfgang Denk wrote:
> Dear Heinrich,
> 
> In message <20171121184503.3193-1-xypron.glpk at gmx.de> you wrote:
> > If 'file' cannot be allocated due to an out of memory
> > situation, do not dereference it.
> > 
> > When debugging this patch also avoids a misleading message
> > "cannot find next direntry, error %d" in case of an out of
> > memory situation. It is sufficent to write
> > "%s: Error, no memory for malloc!\n" in this case.
> > 
> > Reported-by: Alex Sadovsky <nable.maininbox at googlemail.com>
> > Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> > ---
> >  fs/ubifs/ubifs.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/ubifs/ubifs.c b/fs/ubifs/ubifs.c
> > index 4465523d5f..313dee0579 100644
> > --- a/fs/ubifs/ubifs.c
> > +++ b/fs/ubifs/ubifs.c
> > @@ -403,8 +403,7 @@ static int ubifs_finddir(struct super_block *sb, char *dirname,
> >  	dir = kzalloc(sizeof(struct inode), 0);
> >  	if (!file || !dentry || !dir) {
> >  		printf("%s: Error, no memory for malloc!\n", __func__);
> > -		err = -ENOMEM;
> > -		goto out;
> > +		goto out_nomem;
> >  	}
> >  
> >  	dir->i_sb = sb;
> > @@ -424,7 +423,6 @@ static int ubifs_finddir(struct super_block *sb, char *dirname,
> >  		err = PTR_ERR(dent);
> >  		goto out;
> >  	}
> > -
> >  	file->f_pos = key_hash_flash(c, &dent->key);
> >  	file->private_data = dent;
> >  
> > @@ -463,6 +461,7 @@ out:
> >  
> >  out_free:
> >  	kfree(file->private_data);
> > +out_nomem:
> >  	free(file);
> >  	free(dentry);
> >  	free(dir);
> 
> Should you not keep the "err = -ENOMEM;" setting?  Otherwise there
> is no indivcation that an error happened.

It is not obvious from the patch, but value of err is later discarded.
It serves sole purpose of printing debug notice.

> 
> Best regards,
> 
> Wolfgang Denk
> 
> -- 
> DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
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