2008-12-11 19:50:10

by Michael Halcrow

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

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 <[email protected]>

Acked-by: Michael Halcrow <[email protected]>

> ---
> 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;

2008-12-12 01:49:21

by Tim Gardner

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

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 <[email protected]>
>
> Acked-by: Michael Halcrow <[email protected]>
>
>> ---
>> 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: [email protected]' in the commit message. This looks
like a good candidate.

rtg
--
Tim Gardner [email protected]