[patch 16/28] cifs: Increase size of tmp_buf in cifs_readdir to avoid potential overflows

[Greg KH <gregkh@suse.de>]

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2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Suresh Jayaraman <sjayaraman@suse.de>

Commit 7b0c8fcff47a885743125dd843db64af41af5a61 refreshed and use
a #define from commit f58841666bc22e827ca0dcef7b71c7bc2758ce82.

cifs: Increase size of tmp_buf in cifs_readdir to avoid potential overflows

Increase size of tmp_buf to possible maximum to avoid potential
overflows. Also moved UNICODE_NAME_MAX definition so that it can be used
elsewhere.

Pointed-out-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 fs/cifs/cifs_unicode.h |    7 +++++++
 fs/cifs/readdir.c      |    2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

--- a/fs/cifs/cifs_unicode.h
+++ b/fs/cifs/cifs_unicode.h
@@ -64,6 +64,13 @@ int cifs_strtoUCS(__le16 *, const char *
 #endif
 
 /*
+ * To be safe - for UCS to UTF-8 with strings loaded with the rare long
+ * characters alloc more to account for such multibyte target UTF-8
+ * characters.
+ */
+#define UNICODE_NAME_MAX ((4 * NAME_MAX) + 2)
+
+/*
  * UniStrcat:  Concatenate the second string to the first
  *
  * Returns:
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -1075,7 +1075,7 @@ int cifs_readdir(struct file *file, void
 		with the rare long characters alloc more to account for
 		such multibyte target UTF-8 characters. cifs_unicode.c,
 		which actually does the conversion, has the same limit */
-		tmp_buf = kmalloc((2 * NAME_MAX) + 4, GFP_KERNEL);
+		tmp_buf = kmalloc(UNICODE_NAME_MAX, GFP_KERNEL);
 		for (i = 0; (i < num_to_fill) && (rc == 0); i++) {
 			if (current_entry == NULL) {
 				/* evaluate whether this case is an error */