[added to the 4.1 stable tree] afs: Prevent callback expiry timer overflow

[Sasha Levin <Alexander.Levin@xxxxxxxxxxxxx>]

From: Tina Ruchandani <ruchandani.tina@xxxxxxxxx>

This patch has been added to the  stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit 56e714312e7dbd6bb83b2f78d3ec19a404c7649f ]

get_seconds() returns real wall-clock seconds. On 32-bit systems
this value will overflow in year 2038 and beyond. This patch changes
afs_vnode record to use ktime_get_real_seconds() instead, for the
fields cb_expires and cb_expires_at.

Signed-off-by: Tina Ruchandani <ruchandani.tina@xxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 fs/afs/fsclient.c | 2 +-
 fs/afs/inode.c    | 7 ++++---
 fs/afs/internal.h | 4 ++--
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index c2e930ec2888..c775fefe3ffe 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -139,7 +139,7 @@ static void xdr_decode_AFSCallBack(const __be32 **_bp, struct afs_vnode *vnode)
 	vnode->cb_version	= ntohl(*bp++);
 	vnode->cb_expiry	= ntohl(*bp++);
 	vnode->cb_type		= ntohl(*bp++);
-	vnode->cb_expires	= vnode->cb_expiry + get_seconds();
+	vnode->cb_expires	= vnode->cb_expiry + ktime_get_real_seconds();
 	*_bp = bp;
 }
 
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 9580456e8902..2d706612f1f5 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -244,12 +244,13 @@ struct inode *afs_iget(struct super_block *sb, struct key *key,
 			vnode->cb_version = 0;
 			vnode->cb_expiry = 0;
 			vnode->cb_type = 0;
-			vnode->cb_expires = get_seconds();
+			vnode->cb_expires = ktime_get_real_seconds();
 		} else {
 			vnode->cb_version = cb->version;
 			vnode->cb_expiry = cb->expiry;
 			vnode->cb_type = cb->type;
-			vnode->cb_expires = vnode->cb_expiry + get_seconds();
+			vnode->cb_expires = vnode->cb_expiry +
+				ktime_get_real_seconds();
 		}
 	}
 
@@ -322,7 +323,7 @@ int afs_validate(struct afs_vnode *vnode, struct key *key)
 	    !test_bit(AFS_VNODE_CB_BROKEN, &vnode->flags) &&
 	    !test_bit(AFS_VNODE_MODIFIED, &vnode->flags) &&
 	    !test_bit(AFS_VNODE_ZAP_DATA, &vnode->flags)) {
-		if (vnode->cb_expires < get_seconds() + 10) {
+		if (vnode->cb_expires < ktime_get_real_seconds() + 10) {
 			_debug("callback expired");
 			set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
 		} else {
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index c671cdb3acad..1330b2a695ff 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -375,8 +375,8 @@ struct afs_vnode {
 	struct rb_node		server_rb;	/* link in server->fs_vnodes */
 	struct rb_node		cb_promise;	/* link in server->cb_promises */
 	struct work_struct	cb_broken_work;	/* work to be done on callback break */
-	time_t			cb_expires;	/* time at which callback expires */
-	time_t			cb_expires_at;	/* time used to order cb_promise */
+	time64_t		cb_expires;	/* time at which callback expires */
+	time64_t		cb_expires_at;	/* time used to order cb_promise */
 	unsigned		cb_version;	/* callback version */
 	unsigned		cb_expiry;	/* callback expiry time */
 	afs_callback_type_t	cb_type;	/* type of callback */
-- 
2.11.0