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

Greg KH
2009-05-06T22:09:55Z

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

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

From: David Howells <dhowells@redhat.com>

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@redhat.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
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;