cifs: check MaxPathNameComponentLength != 0 before using it

Thanks: Andrew Chadwick

Closes: #880504

debian/changelog

@@ -47,7 +47,11 @@ linux (4.13.11-1) UNRELEASED; urgency=medium
     - [powerpc*] xive: Fix the size of the cpumask used in
       xive_find_target_in_mask()
 
- -- Salvatore Bonaccorso <carnil@debian.org>  Sat, 04 Nov 2017 08:41:02 +0100
+  [ Salvatore Bonaccorso ]
+  * cifs: check MaxPathNameComponentLength != 0 before using it.
+    Thanks to Andrew Chadwick (Closes: #880504)
+
+ -- Salvatore Bonaccorso <carnil@debian.org>  Sat, 04 Nov 2017 09:54:41 +0100
 
 linux (4.13.10-1) unstable; urgency=medium
 

debian/patches/bugfix/all/cifs-check-MaxPathNameComponentLength-0-before-using.patch

@@ -0,0 +1,42 @@
+From: Ronnie Sahlberg <lsahlber@redhat.com>
+Date: Mon, 30 Oct 2017 13:28:03 +1100
+Subject: cifs: check MaxPathNameComponentLength != 0 before using it
+Origin: https://git.kernel.org/linus/f74bc7c6679200a4a83156bb89cbf6c229fe8ec0
+Bug-Debian: https://bugs.debian.org/880504
+
+And fix tcon leak in error path.
+
+Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
+Signed-off-by: Steve French <smfrench@gmail.com>
+CC: Stable <stable@vger.kernel.org>
+Reviewed-by: David Disseldorp <ddiss@samba.org>
+---
+ fs/cifs/dir.c | 5 +++--
+ 1 file changed, 3 insertions(+), 2 deletions(-)
+
+diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
+index e702d48bd023..81ba6e0d88d8 100644
+--- a/fs/cifs/dir.c
++++ b/fs/cifs/dir.c
+@@ -204,7 +204,8 @@ check_name(struct dentry *direntry, struct cifs_tcon *tcon)
+ 	struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
+ 	int i;
+ 
+-	if (unlikely(direntry->d_name.len >
++	if (unlikely(tcon->fsAttrInfo.MaxPathNameComponentLength &&
++		     direntry->d_name.len >
+ 		     le32_to_cpu(tcon->fsAttrInfo.MaxPathNameComponentLength)))
+ 		return -ENAMETOOLONG;
+ 
+@@ -520,7 +521,7 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
+ 
+ 	rc = check_name(direntry, tcon);
+ 	if (rc)
+-		goto out_free_xid;
++		goto out;
+ 
+ 	server = tcon->ses->server;
+ 
+-- 
+2.11.0
+

debian/patches/series

@@ -78,6 +78,7 @@ bugfix/all/fs-add-module_softdep-declarations-for-hard-coded-cr.patch
 bugfix/all/partially-revert-usb-kconfig-using-select-for-usb_co.patch
 bugfix/all/kbuild-include-addtree-remove-quotes-before-matching-path.patch
 bugfix/all/bfq-re-enable-auto-loading-when-built-as-a-module.patch
+bugfix/all/cifs-check-MaxPathNameComponentLength-0-before-using.patch
 
 # Miscellaneous features