Re: [patch] ext4: underflow in alignment check
From: Jan Kara <jack@suse.cz>
Date: 2016-06-20 16:04:14
Also in:
kernel-janitors, lkml
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 <redacted>
How come? (1 << 30) fits even into 32-bit signed type. So where's the problem? Honza
quoted hunk ↗ jump to hunk
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 [off-list ref] SUSE Labs, CR