From: Jan Kara <jack@suse.cz>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-janitors@vger.kernel.org
Subject: Re: [patch] ext4: underflow in alignment check
Date: Mon, 20 Jun 2016 18:02:04 +0200 [thread overview]
Message-ID: <20160620160204.GG6882@quack2.suse.cz> (raw)
In-Reply-To: <20160616070709.GC23129@mwanda>
On Thu 16-06-16 10:07:09, Dan Carpenter wrote:
> My static checker complains that this can underflow if arg is negative
> which is true.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
How come? (1 << 30) fits even into 32-bit signed type. So where's the
problem?
Honza
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index b1a3471..a2a17e9 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1576,7 +1576,7 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
> } else if (token == Opt_min_batch_time) {
> sbi->s_min_batch_time = arg;
> } else if (token == Opt_inode_readahead_blks) {
> - if (arg && (arg > (1 << 30) || !is_power_of_2(arg))) {
> + if (arg && (arg > (1U << 30) || !is_power_of_2(arg))) {
> ext4_msg(sb, KERN_ERR,
> "EXT4-fs: inode_readahead_blks must be "
> "0 or a power of 2 smaller than 2^31");
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2016-06-20 16:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-16 7:07 [patch] ext4: underflow in alignment check Dan Carpenter
2016-06-20 16:02 ` Jan Kara [this message]
2016-06-20 19:53 ` Dan Carpenter
2016-06-21 7:43 ` Jan Kara
2016-06-21 13:06 ` Dan Carpenter
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