Re: [PATCH 2.6] Check return value of copy_to_user in fs/cifs/file.c [Re: Linux 2.6.11-rc4]

[Marcel Sebek]

On Sun, Feb 13, 2005 at 04:44:16PM +0100, Luca wrote:
> Linus Torvalds <torvalds@xxxxxxxx> ha scritto:
> > this is hopefully the last -rc kernel before the real 2.6.11, so please 
> > give it a whirl, and complain loudly about anything broken.
> 
> The following patch against 2.6.11-rc4 fixes this compile time warning:
> 
>  CC [M]  fs/cifs/file.o
> fs/cifs/file.c: In function `cifs_user_read':
> fs/cifs/file.c:1168: warning: ignoring return value of
> `copy_to_user', declared with attribute warn_unused_result
> 
> I also added an explicit check for errors other than -EAGAIN, since
> CIFSSMBRead may return -ENOMEM if it's unable to allocate smb_com_read_rsp;
> in that case we don't want to call copy_to_user with a NULL pointer.
> 
> Signed-off-by: Luca Tettamanti <kronoz@xxxxxxxxxxxxxx>
> 
> --- a/fs/cifs/file.c	2005-02-03 17:58:07.000000000 +0100
> +++ b/fs/cifs/file.c	2005-02-03 18:17:37.000000000 +0100
> @@ -1151,7 +1151,7 @@
>  		current_read_size = min_t(const int,read_size - total_read,cifs_sb->rsize);
>  		rc = -EAGAIN;
>  		smb_read_data = NULL;
> -		while(rc == -EAGAIN) {
> +		while(1) {
>  			if ((open_file->invalidHandle) && (!open_file->closePend)) {
>  				rc = cifs_reopen_file(file->f_dentry->d_inode,
>  					file,TRUE);
> @@ -1164,13 +1164,22 @@
>  				 current_read_size, *poffset,
>  				 &bytes_read, &smb_read_data);
>  
> +			if (rc == -EAGAIN)
> +				continue;
> +			else
> +				break;
> +
>  			pSMBr = (struct smb_com_read_rsp *)smb_read_data;
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Perhaps this line and the following lines are never executed with your
patch, am I right?

> -			copy_to_user(current_offset,smb_read_data + 4/* RFC1001 hdr*/
> +			rc = copy_to_user(current_offset,smb_read_data + 4/* RFC1001 hdr*/
>  				+ le16_to_cpu(pSMBr->DataOffset), bytes_read);
>  			if(smb_read_data) {
>  				cifs_buf_release(smb_read_data);
>  				smb_read_data = NULL;
>  			}
> +			if (rc) {
> +				FreeXid(xid);
> +				return -EFAULT;
> +			}
>  		}
>  		if (rc || (bytes_read == 0)) {
>  			if (total_read) {
> 
> 

-- 
Marcel Sebek
jabber: sebek@xxxxxxxxx                     ICQ: 279852819
linux user number: 307850                 GPG ID: 5F88735E
GPG FP: 0F01 BAB8 3148 94DB B95D  1FCA 8B63 CA06 5F88 735E

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