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Ben Hutchings

2013-Oct-27 20:18 UTC

[Ocfs2-devel] [PATCH] ocfs2: Do not write error flag to user structure we cannot copy from/to

If we failed to copy from the structure, writing back the flags leaks
31 bits of kernel memory (the rest of the ir_flags field).

In any case, if we cannot copy from/to the structure, why should we
expect putting just the flags to work?

Also make sure ocfs2_info_handle_freeinode() returns the right error
code if the copy_to_user() fails.

Compile-tested only.

Signed-off-by: Ben Hutchings <ben at decadent.org.uk>
Cc: stable at vger.kernel.org
Fixes: ddee5cdb70e6 ('Ocfs2: Add new OCFS2_IOC_INFO ioctl for ocfs2
v8.')
---
 fs/ocfs2/ioctl.c | 129 +++++++++++++++++++------------------------------------
 1 file changed, 43 insertions(+), 86 deletions(-)

diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
index fa32ce9..71e2492 100644
--- a/fs/ocfs2/ioctl.c
+++ b/fs/ocfs2/ioctl.c
@@ -34,9 +34,8 @@
 		copy_to_user((typeof(a) __user *)b, &(a), sizeof(a))
 
 /*
- * This call is void because we are already reporting an error that may
- * be -EFAULT.  The error will be returned from the ioctl(2) call.  It's
- * just a best-effort to tell userspace that this request caused the error.
+ * This is just a best-effort to tell userspace that this request
+ * caused the error.
  */
 static inline void o2info_set_request_error(struct ocfs2_info_request *kreq,
 					struct ocfs2_info_request __user *req)
@@ -145,136 +144,105 @@ bail:
 int ocfs2_info_handle_blocksize(struct inode *inode,
 				struct ocfs2_info_request __user *req)
 {
-	int status = -EFAULT;
 	struct ocfs2_info_blocksize oib;
 
 	if (o2info_from_user(oib, req))
-		goto bail;
+		return -EFAULT;
 
 	oib.ib_blocksize = inode->i_sb->s_blocksize;
 
 	o2info_set_request_filled(&oib.ib_req);
 
 	if (o2info_to_user(oib, req))
-		goto bail;
-
-	status = 0;
-bail:
-	if (status)
-		o2info_set_request_error(&oib.ib_req, req);
+		return -EFAULT;
 
-	return status;
+	return 0;
 }
 
 int ocfs2_info_handle_clustersize(struct inode *inode,
 				  struct ocfs2_info_request __user *req)
 {
-	int status = -EFAULT;
 	struct ocfs2_info_clustersize oic;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
 	if (o2info_from_user(oic, req))
-		goto bail;
+		return -EFAULT;
 
 	oic.ic_clustersize = osb->s_clustersize;
 
 	o2info_set_request_filled(&oic.ic_req);
 
 	if (o2info_to_user(oic, req))
-		goto bail;
-
-	status = 0;
-bail:
-	if (status)
-		o2info_set_request_error(&oic.ic_req, req);
+		return -EFAULT;
 
-	return status;
+	return 0;
 }
 
 int ocfs2_info_handle_maxslots(struct inode *inode,
 			       struct ocfs2_info_request __user *req)
 {
-	int status = -EFAULT;
 	struct ocfs2_info_maxslots oim;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
 	if (o2info_from_user(oim, req))
-		goto bail;
+		return -EFAULT;
 
 	oim.im_max_slots = osb->max_slots;
 
 	o2info_set_request_filled(&oim.im_req);
 
 	if (o2info_to_user(oim, req))
-		goto bail;
+		return -EFAULT;
 
-	status = 0;
-bail:
-	if (status)
-		o2info_set_request_error(&oim.im_req, req);
-
-	return status;
+	return 0;
 }
 
 int ocfs2_info_handle_label(struct inode *inode,
 			    struct ocfs2_info_request __user *req)
 {
-	int status = -EFAULT;
 	struct ocfs2_info_label oil;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
 	if (o2info_from_user(oil, req))
-		goto bail;
+		return -EFAULT;
 
 	memcpy(oil.il_label, osb->vol_label, OCFS2_MAX_VOL_LABEL_LEN);
 
 	o2info_set_request_filled(&oil.il_req);
 
 	if (o2info_to_user(oil, req))
-		goto bail;
+		return -EFAULT;
 
-	status = 0;
-bail:
-	if (status)
-		o2info_set_request_error(&oil.il_req, req);
-
-	return status;
+	return 0;
 }
 
 int ocfs2_info_handle_uuid(struct inode *inode,
 			   struct ocfs2_info_request __user *req)
 {
-	int status = -EFAULT;
 	struct ocfs2_info_uuid oiu;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
 	if (o2info_from_user(oiu, req))
-		goto bail;
+		return -EFAULT;
 
 	memcpy(oiu.iu_uuid_str, osb->uuid_str, OCFS2_TEXT_UUID_LEN + 1);
 
 	o2info_set_request_filled(&oiu.iu_req);
 
 	if (o2info_to_user(oiu, req))
-		goto bail;
-
-	status = 0;
-bail:
-	if (status)
-		o2info_set_request_error(&oiu.iu_req, req);
+		return -EFAULT;
 
-	return status;
+	return 0;
 }
 
 int ocfs2_info_handle_fs_features(struct inode *inode,
 				  struct ocfs2_info_request __user *req)
 {
-	int status = -EFAULT;
 	struct ocfs2_info_fs_features oif;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
 	if (o2info_from_user(oif, req))
-		goto bail;
+		return -EFAULT;
 
 	oif.if_compat_features = osb->s_feature_compat;
 	oif.if_incompat_features = osb->s_feature_incompat;
@@ -283,39 +251,28 @@ int ocfs2_info_handle_fs_features(struct inode *inode,
 	o2info_set_request_filled(&oif.if_req);
 
 	if (o2info_to_user(oif, req))
-		goto bail;
+		return -EFAULT;
 
-	status = 0;
-bail:
-	if (status)
-		o2info_set_request_error(&oif.if_req, req);
-
-	return status;
+	return 0;
 }
 
 int ocfs2_info_handle_journal_size(struct inode *inode,
 				   struct ocfs2_info_request __user *req)
 {
-	int status = -EFAULT;
 	struct ocfs2_info_journal_size oij;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
 	if (o2info_from_user(oij, req))
-		goto bail;
+		return -EFAULT;
 
 	oij.ij_journal_size = i_size_read(osb->journal->j_inode);
 
 	o2info_set_request_filled(&oij.ij_req);
 
 	if (o2info_to_user(oij, req))
-		goto bail;
+		return -EFAULT;
 
-	status = 0;
-bail:
-	if (status)
-		o2info_set_request_error(&oij.ij_req, req);
-
-	return status;
+	return 0;
 }
 
 int ocfs2_info_scan_inode_alloc(struct ocfs2_super *osb,
@@ -371,7 +328,7 @@ int ocfs2_info_handle_freeinode(struct inode *inode,
 	u32 i;
 	u64 blkno = -1;
 	char namebuf[40];
-	int status = -EFAULT, type = INODE_ALLOC_SYSTEM_INODE;
+	int status, type = INODE_ALLOC_SYSTEM_INODE;
 	struct ocfs2_info_freeinode *oifi = NULL;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 	struct inode *inode_alloc = NULL;
@@ -383,8 +340,10 @@ int ocfs2_info_handle_freeinode(struct inode *inode,
 		goto out_err;
 	}
 
-	if (o2info_from_user(*oifi, req))
-		goto bail;
+	if (o2info_from_user(*oifi, req)) {
+		status = -EFAULT;
+		goto out_free;
+	}
 
 	oifi->ifi_slotnum = osb->max_slots;
 
@@ -421,14 +380,16 @@ int ocfs2_info_handle_freeinode(struct inode *inode,
 
 	o2info_set_request_filled(&oifi->ifi_req);
 
-	if (o2info_to_user(*oifi, req))
-		goto bail;
+	if (o2info_to_user(*oifi, req)) {
+		status = -EFAULT;
+		goto out_free;
+	}
 
 	status = 0;
 bail:
 	if (status)
 		o2info_set_request_error(&oifi->ifi_req, req);
-
+out_free:
 	kfree(oifi);
 out_err:
 	return status;
@@ -655,7 +616,7 @@ int ocfs2_info_handle_freefrag(struct inode *inode,
 {
 	u64 blkno = -1;
 	char namebuf[40];
-	int status = -EFAULT, type = GLOBAL_BITMAP_SYSTEM_INODE;
+	int status, type = GLOBAL_BITMAP_SYSTEM_INODE;
 
 	struct ocfs2_info_freefrag *oiff;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
@@ -668,8 +629,10 @@ int ocfs2_info_handle_freefrag(struct inode *inode,
 		goto out_err;
 	}
 
-	if (o2info_from_user(*oiff, req))
-		goto bail;
+	if (o2info_from_user(*oiff, req)) {
+		status = -EFAULT;
+		goto out_free;
+	}
 	/*
 	 * chunksize from userspace should be power of 2.
 	 */
@@ -708,14 +671,14 @@ int ocfs2_info_handle_freefrag(struct inode *inode,
 
 	if (o2info_to_user(*oiff, req)) {
 		status = -EFAULT;
-		goto bail;
+		goto out_free;
 	}
 
 	status = 0;
 bail:
 	if (status)
 		o2info_set_request_error(&oiff->iff_req, req);
-
+out_free:
 	kfree(oiff);
 out_err:
 	return status;
@@ -724,23 +687,17 @@ out_err:
 int ocfs2_info_handle_unknown(struct inode *inode,
 			      struct ocfs2_info_request __user *req)
 {
-	int status = -EFAULT;
 	struct ocfs2_info_request oir;
 
 	if (o2info_from_user(oir, req))
-		goto bail;
+		return -EFAULT;
 
 	o2info_clear_request_filled(&oir);
 
 	if (o2info_to_user(oir, req))
-		goto bail;
+		return -EFAULT;
 
-	status = 0;
-bail:
-	if (status)
-		o2info_set_request_error(&oir, req);
-
-	return status;
+	return 0;
 }
 
 /*

-- 
Ben Hutchings
If at first you don't succeed, you're doing about average.
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Joel Becker

2013-Nov-07 11:22 UTC

head link

[Ocfs2-devel] [PATCH] ocfs2: Do not write error flag to user structure we cannot copy from/to

On Sun, Oct 27, 2013 at 08:18:02PM +0000, Ben Hutchings
wrote:> If we failed to copy from the structure, writing back the flags leaks
> 31 bits of kernel memory (the rest of the ir_flags field).
> 
> In any case, if we cannot copy from/to the structure, why should we
> expect putting just the flags to work?
The first issue could be fixed; we could clear the flags.  The second
issue is what matters.  If we're getting EFAULT, we're not going to be
moving any flags around.  We should just return the EFAULT and be done
with it.
 > Also make sure ocfs2_info_handle_freeinode() returns the right error
> code if the copy_to_user() fails.
> 
> Compile-tested only.
> 
> Signed-off-by: Ben Hutchings <ben at decadent.org.uk>
> Cc: stable at vger.kernel.org
> Fixes: ddee5cdb70e6 ('Ocfs2: Add new OCFS2_IOC_INFO ioctl for ocfs2
v8.')
I can't recommend this for stable if it hasn't actually been tested.
There is no exposure; as you point out, the put_user() will fail if the
get_user() is failing.

Send me a version without stable and I'll Ack it.

Joel

> ---
>  fs/ocfs2/ioctl.c | 129
+++++++++++++++++++------------------------------------
>  1 file changed, 43 insertions(+), 86 deletions(-)
> 
> diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
> index fa32ce9..71e2492 100644
> --- a/fs/ocfs2/ioctl.c
> +++ b/fs/ocfs2/ioctl.c
> @@ -34,9 +34,8 @@
>  		copy_to_user((typeof(a) __user *)b, &(a), sizeof(a))
>  
>  /*
> - * This call is void because we are already reporting an error that may
> - * be -EFAULT.  The error will be returned from the ioctl(2) call. 
It's
> - * just a best-effort to tell userspace that this request caused the
error.
> + * This is just a best-effort to tell userspace that this request
> + * caused the error.
>   */
>  static inline void o2info_set_request_error(struct ocfs2_info_request
*kreq,
>  					struct ocfs2_info_request __user *req)
> @@ -145,136 +144,105 @@ bail:
>  int ocfs2_info_handle_blocksize(struct inode *inode,
>  				struct ocfs2_info_request __user *req)
>  {
> -	int status = -EFAULT;
>  	struct ocfs2_info_blocksize oib;
>  
>  	if (o2info_from_user(oib, req))
> -		goto bail;
> +		return -EFAULT;
>  
>  	oib.ib_blocksize = inode->i_sb->s_blocksize;
>  
>  	o2info_set_request_filled(&oib.ib_req);
>  
>  	if (o2info_to_user(oib, req))
> -		goto bail;
> -
> -	status = 0;
> -bail:
> -	if (status)
> -		o2info_set_request_error(&oib.ib_req, req);
> +		return -EFAULT;
>  
> -	return status;
> +	return 0;
>  }
>  
>  int ocfs2_info_handle_clustersize(struct inode *inode,
>  				  struct ocfs2_info_request __user *req)
>  {
> -	int status = -EFAULT;
>  	struct ocfs2_info_clustersize oic;
>  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>  
>  	if (o2info_from_user(oic, req))
> -		goto bail;
> +		return -EFAULT;
>  
>  	oic.ic_clustersize = osb->s_clustersize;
>  
>  	o2info_set_request_filled(&oic.ic_req);
>  
>  	if (o2info_to_user(oic, req))
> -		goto bail;
> -
> -	status = 0;
> -bail:
> -	if (status)
> -		o2info_set_request_error(&oic.ic_req, req);
> +		return -EFAULT;
>  
> -	return status;
> +	return 0;
>  }
>  
>  int ocfs2_info_handle_maxslots(struct inode *inode,
>  			       struct ocfs2_info_request __user *req)
>  {
> -	int status = -EFAULT;
>  	struct ocfs2_info_maxslots oim;
>  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>  
>  	if (o2info_from_user(oim, req))
> -		goto bail;
> +		return -EFAULT;
>  
>  	oim.im_max_slots = osb->max_slots;
>  
>  	o2info_set_request_filled(&oim.im_req);
>  
>  	if (o2info_to_user(oim, req))
> -		goto bail;
> +		return -EFAULT;
>  
> -	status = 0;
> -bail:
> -	if (status)
> -		o2info_set_request_error(&oim.im_req, req);
> -
> -	return status;
> +	return 0;
>  }
>  
>  int ocfs2_info_handle_label(struct inode *inode,
>  			    struct ocfs2_info_request __user *req)
>  {
> -	int status = -EFAULT;
>  	struct ocfs2_info_label oil;
>  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>  
>  	if (o2info_from_user(oil, req))
> -		goto bail;
> +		return -EFAULT;
>  
>  	memcpy(oil.il_label, osb->vol_label, OCFS2_MAX_VOL_LABEL_LEN);
>  
>  	o2info_set_request_filled(&oil.il_req);
>  
>  	if (o2info_to_user(oil, req))
> -		goto bail;
> +		return -EFAULT;
>  
> -	status = 0;
> -bail:
> -	if (status)
> -		o2info_set_request_error(&oil.il_req, req);
> -
> -	return status;
> +	return 0;
>  }
>  
>  int ocfs2_info_handle_uuid(struct inode *inode,
>  			   struct ocfs2_info_request __user *req)
>  {
> -	int status = -EFAULT;
>  	struct ocfs2_info_uuid oiu;
>  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>  
>  	if (o2info_from_user(oiu, req))
> -		goto bail;
> +		return -EFAULT;
>  
>  	memcpy(oiu.iu_uuid_str, osb->uuid_str, OCFS2_TEXT_UUID_LEN + 1);
>  
>  	o2info_set_request_filled(&oiu.iu_req);
>  
>  	if (o2info_to_user(oiu, req))
> -		goto bail;
> -
> -	status = 0;
> -bail:
> -	if (status)
> -		o2info_set_request_error(&oiu.iu_req, req);
> +		return -EFAULT;
>  
> -	return status;
> +	return 0;
>  }
>  
>  int ocfs2_info_handle_fs_features(struct inode *inode,
>  				  struct ocfs2_info_request __user *req)
>  {
> -	int status = -EFAULT;
>  	struct ocfs2_info_fs_features oif;
>  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>  
>  	if (o2info_from_user(oif, req))
> -		goto bail;
> +		return -EFAULT;
>  
>  	oif.if_compat_features = osb->s_feature_compat;
>  	oif.if_incompat_features = osb->s_feature_incompat;
> @@ -283,39 +251,28 @@ int ocfs2_info_handle_fs_features(struct inode
*inode,
>  	o2info_set_request_filled(&oif.if_req);
>  
>  	if (o2info_to_user(oif, req))
> -		goto bail;
> +		return -EFAULT;
>  
> -	status = 0;
> -bail:
> -	if (status)
> -		o2info_set_request_error(&oif.if_req, req);
> -
> -	return status;
> +	return 0;
>  }
>  
>  int ocfs2_info_handle_journal_size(struct inode *inode,
>  				   struct ocfs2_info_request __user *req)
>  {
> -	int status = -EFAULT;
>  	struct ocfs2_info_journal_size oij;
>  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>  
>  	if (o2info_from_user(oij, req))
> -		goto bail;
> +		return -EFAULT;
>  
>  	oij.ij_journal_size = i_size_read(osb->journal->j_inode);
>  
>  	o2info_set_request_filled(&oij.ij_req);
>  
>  	if (o2info_to_user(oij, req))
> -		goto bail;
> +		return -EFAULT;
>  
> -	status = 0;
> -bail:
> -	if (status)
> -		o2info_set_request_error(&oij.ij_req, req);
> -
> -	return status;
> +	return 0;
>  }
>  
>  int ocfs2_info_scan_inode_alloc(struct ocfs2_super *osb,
> @@ -371,7 +328,7 @@ int ocfs2_info_handle_freeinode(struct inode *inode,
>  	u32 i;
>  	u64 blkno = -1;
>  	char namebuf[40];
> -	int status = -EFAULT, type = INODE_ALLOC_SYSTEM_INODE;
> +	int status, type = INODE_ALLOC_SYSTEM_INODE;
>  	struct ocfs2_info_freeinode *oifi = NULL;
>  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>  	struct inode *inode_alloc = NULL;
> @@ -383,8 +340,10 @@ int ocfs2_info_handle_freeinode(struct inode *inode,
>  		goto out_err;
>  	}
>  
> -	if (o2info_from_user(*oifi, req))
> -		goto bail;
> +	if (o2info_from_user(*oifi, req)) {
> +		status = -EFAULT;
> +		goto out_free;
> +	}
>  
>  	oifi->ifi_slotnum = osb->max_slots;
>  
> @@ -421,14 +380,16 @@ int ocfs2_info_handle_freeinode(struct inode *inode,
>  
>  	o2info_set_request_filled(&oifi->ifi_req);
>  
> -	if (o2info_to_user(*oifi, req))
> -		goto bail;
> +	if (o2info_to_user(*oifi, req)) {
> +		status = -EFAULT;
> +		goto out_free;
> +	}
>  
>  	status = 0;
>  bail:
>  	if (status)
>  		o2info_set_request_error(&oifi->ifi_req, req);
> -
> +out_free:
>  	kfree(oifi);
>  out_err:
>  	return status;
> @@ -655,7 +616,7 @@ int ocfs2_info_handle_freefrag(struct inode *inode,
>  {
>  	u64 blkno = -1;
>  	char namebuf[40];
> -	int status = -EFAULT, type = GLOBAL_BITMAP_SYSTEM_INODE;
> +	int status, type = GLOBAL_BITMAP_SYSTEM_INODE;
>  
>  	struct ocfs2_info_freefrag *oiff;
>  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
> @@ -668,8 +629,10 @@ int ocfs2_info_handle_freefrag(struct inode *inode,
>  		goto out_err;
>  	}
>  
> -	if (o2info_from_user(*oiff, req))
> -		goto bail;
> +	if (o2info_from_user(*oiff, req)) {
> +		status = -EFAULT;
> +		goto out_free;
> +	}
>  	/*
>  	 * chunksize from userspace should be power of 2.
>  	 */
> @@ -708,14 +671,14 @@ int ocfs2_info_handle_freefrag(struct inode *inode,
>  
>  	if (o2info_to_user(*oiff, req)) {
>  		status = -EFAULT;
> -		goto bail;
> +		goto out_free;
>  	}
>  
>  	status = 0;
>  bail:
>  	if (status)
>  		o2info_set_request_error(&oiff->iff_req, req);
> -
> +out_free:
>  	kfree(oiff);
>  out_err:
>  	return status;
> @@ -724,23 +687,17 @@ out_err:
>  int ocfs2_info_handle_unknown(struct inode *inode,
>  			      struct ocfs2_info_request __user *req)
>  {
> -	int status = -EFAULT;
>  	struct ocfs2_info_request oir;
>  
>  	if (o2info_from_user(oir, req))
> -		goto bail;
> +		return -EFAULT;
>  
>  	o2info_clear_request_filled(&oir);
>  
>  	if (o2info_to_user(oir, req))
> -		goto bail;
> +		return -EFAULT;
>  
> -	status = 0;
> -bail:
> -	if (status)
> -		o2info_set_request_error(&oir, req);
> -
> -	return status;
> +	return 0;
>  }
>  
>  /*
> 
> -- 
> Ben Hutchings
> If at first you don't succeed, you're doing about average.


-- 

Life's Little Instruction Book #94

	"Make it a habit to do nice things for people who 
	 will never find out."

			http://www.jlbec.org/
			jlbec at evilplan.org

Ocfs2 devel - Oct 2013 - [PATCH] ocfs2: Do not write error flag to user structure we cannot copy from/to

[Ocfs2-devel] [PATCH] ocfs2: Do not write error flag to user structure we cannot copy from/to

[Ocfs2-devel] [PATCH] ocfs2: Do not write error flag to user structure we cannot copy from/to