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

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Message-ID: <alpine.LFD.2.00.1101031202080.2815@dhcp-lab-213.englab.brq.redhat.com>
Date:	Mon, 3 Jan 2011 12:02:53 +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 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
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