Re: [PATCH] eCryptfs: check readlink result was not an error before using it

[Tim Gardner <tim.gardner@canonical.com>]

Michael Halcrow wrote:
> On Thu, Dec 11, 2008 at 07:16:26PM +0000, Duane Griffin wrote:
>> The result from readlink is being used to index into the link name
>> buffer without checking whether it is a valid length. If readlink
>> returns an error this will fault or cause memory corruption.
>>
>> Signed-off-by: Duane Griffin <duaneg@dghda.com>
> 
> Acked-by: Michael Halcrow <mhalcrow@us.ibm.com>
> 
>> ---
>>  fs/ecryptfs/inode.c |    3 ++-
>>  1 files changed, 2 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
>> index 89209f0..5e78fc1 100644
>> --- a/fs/ecryptfs/inode.c
>> +++ b/fs/ecryptfs/inode.c
>> @@ -673,10 +673,11 @@ static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
>>  	ecryptfs_printk(KERN_DEBUG, "Calling readlink w/ "
>>  			"dentry->d_name.name = [%s]\n", dentry->d_name.name);
>>  	rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
>> -	buf[rc] = '\0';
>>  	set_fs(old_fs);
>>  	if (rc < 0)
>>  		goto out_free;
>> +	else
>> +		buf[rc] = '\0';
>>  	rc = 0;
>>  	nd_set_link(nd, buf);
>>  	goto out;
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Please add 'Cc: stable@kernel.org' in the commit message. This looks
like a good candidate.

rtg
-- 
Tim Gardner tim.gardner@canonical.com