Patch "CIFS: Fix too big maxBuf size for SMB3 mounts" has been added to the 3.13-stable tree

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This is a note to let you know that I've just added the patch titled

    CIFS: Fix too big maxBuf size for SMB3 mounts

to the 3.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     cifs-fix-too-big-maxbuf-size-for-smb3-mounts.patch
and it can be found in the queue-3.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 2365c4eaf077c48574ab6f143960048fc0f31518 Mon Sep 17 00:00:00 2001
From: Pavel Shilovsky <piastry@xxxxxxxxxxx>
Date: Fri, 14 Feb 2014 13:31:02 +0400
Subject: CIFS: Fix too big maxBuf size for SMB3 mounts

From: Pavel Shilovsky <piastry@xxxxxxxxxxx>

commit 2365c4eaf077c48574ab6f143960048fc0f31518 upstream.

SMB3 servers can respond with MaxTransactSize of more than 4M
that can cause a memory allocation error returned from kmalloc
in a lock codepath. Also the client doesn't support multicredit
requests now and allows buffer sizes of 65536 bytes only. Set
MaxTransactSize to this maximum supported value.

Signed-off-by: Pavel Shilovsky <piastry@xxxxxxxxxxx>
Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Steve French <smfrench@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/cifs/smb2glob.h |    3 +++
 fs/cifs/smb2ops.c  |   14 ++++----------
 fs/cifs/smb2pdu.c  |    4 +++-
 3 files changed, 10 insertions(+), 11 deletions(-)

--- a/fs/cifs/smb2glob.h
+++ b/fs/cifs/smb2glob.h
@@ -57,4 +57,7 @@
 #define SMB2_CMACAES_SIZE (16)
 #define SMB3_SIGNKEY_SIZE (16)
 
+/* Maximum buffer size value we can send with 1 credit */
+#define SMB2_MAX_BUFFER_SIZE 65536
+
 #endif	/* _SMB2_GLOB_H */
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -182,11 +182,8 @@ smb2_negotiate_wsize(struct cifs_tcon *t
 	/* start with specified wsize, or default */
 	wsize = volume_info->wsize ? volume_info->wsize : CIFS_DEFAULT_IOSIZE;
 	wsize = min_t(unsigned int, wsize, server->max_write);
-	/*
-	 * limit write size to 2 ** 16, because we don't support multicredit
-	 * requests now.
-	 */
-	wsize = min_t(unsigned int, wsize, 2 << 15);
+	/* set it to the maximum buffer size value we can send with 1 credit */
+	wsize = min_t(unsigned int, wsize, SMB2_MAX_BUFFER_SIZE);
 
 	return wsize;
 }
@@ -200,11 +197,8 @@ smb2_negotiate_rsize(struct cifs_tcon *t
 	/* start with specified rsize, or default */
 	rsize = volume_info->rsize ? volume_info->rsize : CIFS_DEFAULT_IOSIZE;
 	rsize = min_t(unsigned int, rsize, server->max_read);
-	/*
-	 * limit write size to 2 ** 16, because we don't support multicredit
-	 * requests now.
-	 */
-	rsize = min_t(unsigned int, rsize, 2 << 15);
+	/* set it to the maximum buffer size value we can send with 1 credit */
+	rsize = min_t(unsigned int, rsize, SMB2_MAX_BUFFER_SIZE);
 
 	return rsize;
 }
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -413,7 +413,9 @@ SMB2_negotiate(const unsigned int xid, s
 
 	/* SMB2 only has an extended negflavor */
 	server->negflavor = CIFS_NEGFLAVOR_EXTENDED;
-	server->maxBuf = le32_to_cpu(rsp->MaxTransactSize);
+	/* set it to the maximum buffer size value we can send with 1 credit */
+	server->maxBuf = min_t(unsigned int, le32_to_cpu(rsp->MaxTransactSize),
+			       SMB2_MAX_BUFFER_SIZE);
 	server->max_read = le32_to_cpu(rsp->MaxReadSize);
 	server->max_write = le32_to_cpu(rsp->MaxWriteSize);
 	/* BB Do we need to validate the SecurityMode? */


Patches currently in stable-queue which might be from piastry@xxxxxxxxxxx are

queue-3.13/cifs-fix-too-big-maxbuf-size-for-smb3-mounts.patch
queue-3.13/cifs-ensure-that-uncached-writes-handle-unmapped-areas-correctly.patch
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