linux-ext4 - Re: [PATCH 02/10] ext2fs: Fix overflow when checking s_inodes_count in ext2fs

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Date:   Sun, 3 Jun 2018 22:21:49 -0600
From:   Andreas Dilger <adilger@...ger.ca>
To:     Jan Kara <jack@...e.cz>
Cc:     Ted Tso <tytso@....edu>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 02/10] ext2fs: Fix overflow when checking s_inodes_count
 in ext2fs_open()

On May 30, 2018, at 6:51 AM, Jan Kara <jack@...e.cz> wrote:
> 
> The check whether s_inodes_count is correct in ext2fs_open() can
> overflow and thus not catch all problematic cases. Fix the test.
> 
> Signed-off-by: Jan Kara <jack@...e.cz>

Not sure if "__u64" is exactly the best type there, since that is
normally for on-disk types.  Maybe "u64" or "unsigned long long"
would be better, but not really a reason to redo the patch by itself.

Reviewed-by: Andreas Dilger <adilger@...ger.ca>

> ---
> lib/ext2fs/openfs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
> index 532e70f7f645..e9ad0cd1a2c6 100644
> --- a/lib/ext2fs/openfs.c
> +++ b/lib/ext2fs/openfs.c
> @@ -386,7 +386,7 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
> 		goto cleanup;
> 	}
> 	fs->group_desc_count = 	groups_cnt;
> -	if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
> +	if ((__u64)fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
> 	    fs->super->s_inodes_count) {
> 		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
> 		goto cleanup;
> --
> 2.13.6
> 


Cheers, Andreas






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