ipc: shm: fix information leak to userland

commit 3af54c9bd9e6f14f896aac1bb0e8405ae0bc7a44 upstream.

The shmid_ds structure is copied to userland with shm_unused{,2,3}
fields unitialized.  It leads to leaking of contents of kernel stack
memory.

Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/ipc/shm.c b/ipc/shm.c
index e9b039f74129e3e5e47d34c1e91a128b29fa45df..d30732c97599d6e0a516ccfc305cef1d76bc2304 100644 (file)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -474,6 +474,7 @@ static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_
            {
                struct shmid_ds out;
 
+               memset(&out, 0, sizeof(out));
                ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
                out.shm_segsz   = in->shm_segsz;
                out.shm_atime   = in->shm_atime;