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SubjectRe: [PATCH 2.6] Check return value of copy_to_user in fs/cifs/file.c [Re: Linux 2.6.11-rc4]
Il Sun, Feb 13, 2005 at 06:28:38PM +0100, Marcel Sebek ha scritto: 
> > @@ -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?

Yes, you are. Let's try again:

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@kronoz.cjb.net>

--- a/fs/cifs/file.c 2005-02-03 17:58:07.000000000 +0100
+++ b/fs/cifs/file.c 2005-02-13 21:18:01.000000000 +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;
+ if (rc)
+ break;
+
pSMBr = (struct smb_com_read_rsp *)smb_read_data;
- 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) {

Luca
--
Home: http://kronoz.cjb.net
"La teoria e` quando sappiamo come funzionano le cose ma non funzionano.
La pratica e` quando le cose funzionano ma non sappiamo perche`.
Abbiamo unito la teoria e la pratica: le cose non funzionano piu` e non
sappiamo il perche`." -- A. Einstein
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