linux-ext4 - Re: [PATCH] ext4: Fix check for block being out of directory size

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Message-ID: <Yw+3CfOL6YtYKHZl@eldamar.lan>
Date:   Wed, 31 Aug 2022 21:31:21 +0200
From:   Salvatore Bonaccorso <carnil@...ian.org>
To:     Lukas Czerner <lczerner@...hat.com>
Cc:     Jan Kara <jack@...e.cz>, Ted Tso <tytso@....edu>,
        linux-ext4@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] ext4: Fix check for block being out of directory size

Hi,

On Tue, Aug 23, 2022 at 12:00:19PM +0200, Lukas Czerner wrote:
> On Mon, Aug 22, 2022 at 01:48:32PM +0200, Jan Kara wrote:
> > The check in __ext4_read_dirblock() for block being outside of directory
> > size was wrong because it compared block number against directory size
> > in bytes. Fix it.
> 
> Good catch, thanks!
> 
> Reviewed-by: Lukas Czerner <lczerner@...hat.com>
> 
> > 
> > Fixes: 65f8ea4cd57d ("ext4: check if directory block is within i_size")
> > CVE: CVE-2022-1184
> > CC: stable@...r.kernel.org
> > Signed-off-by: Jan Kara <jack@...e.cz>
> > ---
> >  fs/ext4/namei.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> > index 3a31b662f661..bc2e0612ec32 100644
> > --- a/fs/ext4/namei.c
> > +++ b/fs/ext4/namei.c
> > @@ -126,7 +126,7 @@ static struct buffer_head *__ext4_read_dirblock(struct inode *inode,
> >  	struct ext4_dir_entry *dirent;
> >  	int is_dx_block = 0;
> >  
> > -	if (block >= inode->i_size) {
> > +	if (block >= inode->i_size >> inode->i_blkbits) {
> >  		ext4_error_inode(inode, func, line, block,
> >  		       "Attempting to read directory block (%u) that is past i_size (%llu)",
> >  		       block, inode->i_size);

Ted, is this on your radar to get applied for mainline and to the
stable trees?

Regards,
Salvatore