[bug report] cifs: improve symlink handling for smb2+

[bug report] cifs: improve symlink handling for smb2+

[Dan Carpenter]

Hello Paulo Alcantara,

This is a semi-automatic email about new static checker warnings.

The patch d87ee26fa912: "cifs: improve symlink handling for smb2+"
from Oct 3, 2022, leads to the following Smatch complaint:

    fs/cifs/smb2file.c:126 smb2_open_file()
    warn: variable dereferenced before check 'oparms->cifs_sb' (see line 112)

fs/cifs/smb2file.c
   111	
   112		smb2_path = cifs_convert_path_to_utf16(oparms->path, oparms->cifs_sb);
                                                                     ^^^^^^^^^^^^^^^
The existing code dereferences "oparms->cifs_sb" without checking for
NULL

   113		if (smb2_path == NULL)
   114			return -ENOMEM;
   115	
   116		oparms->desired_access |= FILE_READ_ATTRIBUTES;
   117		smb2_oplock = SMB2_OPLOCK_LEVEL_BATCH;
   118	
   119		rc = SMB2_open(xid, oparms, smb2_path, &smb2_oplock, smb2_data, NULL, &err_iov,
   120			       &err_buftype);
   121		if (rc && data) {
   122			struct smb2_hdr *hdr = err_iov.iov_base;
   123	
   124			if (unlikely(!err_iov.iov_base || err_buftype == CIFS_NO_BUFFER))
   125				rc = -ENOMEM;
   126			else if (hdr->Status == STATUS_STOPPED_ON_SYMLINK && oparms->cifs_sb) {
                                                                             ^^^^^^^^^^^^^^^
so presumably this new NULL check can be deleted as well.

   127				rc = smb2_parse_symlink_response(oparms->cifs_sb, &err_iov,
   128								 &data->symlink_target);

regards,
dan carpenter

[PATCH] cifs: fix static checker warning

[Paulo Alcantara]

Remove unnecessary NULL check of oparam->cifs_sb when parsing symlink
error response as it's already set by all smb2_open_file() callers and
deferenced earlier.

This fixes below report:

  fs/cifs/smb2file.c:126 smb2_open_file()
  warn: variable dereferenced before check 'oparms->cifs_sb' (see line 112)

Link: https://lore.kernel.org/r/Y0kt42j2tdpYakRu@kili
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
---
 fs/cifs/smb2file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/smb2file.c b/fs/cifs/smb2file.c
index 4992b43616a7..ffbd9a99fc12 100644
--- a/fs/cifs/smb2file.c
+++ b/fs/cifs/smb2file.c
@@ -123,7 +123,7 @@ int smb2_open_file(const unsigned int xid, struct cifs_open_parms *oparms, __u32
 
 		if (unlikely(!err_iov.iov_base || err_buftype == CIFS_NO_BUFFER))
 			rc = -ENOMEM;
-		else if (hdr->Status == STATUS_STOPPED_ON_SYMLINK && oparms->cifs_sb) {
+		else if (hdr->Status == STATUS_STOPPED_ON_SYMLINK) {
 			rc = smb2_parse_symlink_response(oparms->cifs_sb, &err_iov,
 							 &data->symlink_target);
 			if (!rc) {
-- 
2.37.3