[patch 36/58] Annotate struct fs_structs usage count restriction

[Greg KH]

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

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

From: David Howells <dhowells@xxxxxxxxxx>

commit 795e2fe0a3b69dbc040d7efcf517e0cbad6901d0 upstream.

Annotate struct fs_struct's usage count to indicate the restrictions upon it.
It may not be incremented, except by clone(CLONE_FS), as this affects the
check in check_unsafe_exec() in fs/exec.c.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx>
Cc: stable@xxxxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 include/linux/fs_struct.h |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/include/linux/fs_struct.h
+++ b/include/linux/fs_struct.h
@@ -4,7 +4,10 @@
 #include <linux/path.h>
 
 struct fs_struct {
-	atomic_t count;
+	atomic_t count;	/* This usage count is used by check_unsafe_exec() for
+			 * security checking purposes - therefore it may not be
+			 * incremented, except by clone(CLONE_FS).
+			 */
 	rwlock_t lock;
 	int umask;
 	struct path root, pwd;


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