linux-ext4 - Re: [PATCH] ext4: fix possible overflow in ext4_trim

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Date:	Mon, 3 Jan 2011 12:09:35 +0100 (CET)
From:	Lukas Czerner <lczerner@...hat.com>
To:	Lukas Czerner <lczerner@...hat.com>
cc:	linux-ext4@...r.kernel.org, tytso@....edu
Subject: Re: [PATCH] ext4: fix possible overflow in ext4_trim_fs()

On Mon, 3 Jan 2011, Lukas Czerner wrote:

> On Thu, 25 Nov 2010, Lukas Czerner wrote:
> 
> > When determining last group through ext4_get_group_no_and_offset() the
> > result may be wrong in cases when range->start and range-len are too
> > big, because it may overflow when summing up those two numbers.
> > 
> > Fix that by checking range->len and limit its value to
> > ext4_blocks_count(). This commit was tested by myself with expected
> > result.
> > 
> > Signed-off-by: Lukas Czerner <lczerner@...hat.com>
> > ---
> >  fs/ext4/mballoc.c |    4 ++++
> >  1 files changed, 4 insertions(+), 0 deletions(-)
> > 
> > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> > index 5b4d4e3..7b05d92 100644
> > --- a/fs/ext4/mballoc.c
> > +++ b/fs/ext4/mballoc.c
> > @@ -4819,6 +4819,7 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
> >  	ext4_group_t group, ngroups = ext4_get_groups_count(sb);
> >  	ext4_grpblk_t cnt = 0, first_block, last_block;
> >  	uint64_t start, len, minlen, trimmed;
> > +	ext4_fsblk_t blocks_count = ext4_blocks_count(EXT4_SB(sb)->s_es);
> >  	int ret = 0;
> >  
> >  	start = range->start >> sb->s_blocksize_bits;
> > @@ -4826,6 +4827,9 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
> >  	minlen = range->minlen >> sb->s_blocksize_bits;
> >  	trimmed = 0;
> >  
> > +	if (len > blocks_count)
> > +		len = blocks_count - start;
> > +
> >  	if (unlikely(minlen > EXT4_BLOCKS_PER_GROUP(sb)))
> >  		return -EINVAL;
> >  
> > 
> 
> Hi Ted,
> 
> what is the status of this one?
> 
> Thanks!
> -Lukas
> 

Oh, please ignore this, I just found "already applied" message. Sorry
for the noise.

-Lukas
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