[PATCH] ipc: initialize structure memory to zero for shmctl

Kees Cook
2010-10-07T00:11:19Z

The old shm interface will leak a few bytes of stack contents. Explicitly
initialize the structure to zero-fill the untouched fields.

Signed-off-by: Kees Cook <kees.cook@canonical.com>
---
ipc/shm.c | 17 +++++++++--------
1 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/ipc/shm.c b/ipc/shm.c
index 52ed77e..d2ee426 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -471,16 +471,17 @@ static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_
return copy_to_user(buf, in, sizeof(*in));
case IPC_OLD:
{
- struct shmid_ds out;
+ struct shmid_ds out = {
+ .shm_segsz = in->shm_segsz,
+ .shm_atime = in->shm_atime,
+ .shm_dtime = in->shm_dtime,
+ .shm_ctime = in->shm_ctime,
+ .shm_cpid = in->shm_cpid,
+ .shm_lpid = in->shm_lpid,
+ .shm_nattch = in->shm_nattch,
+ };

ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
- out.shm_segsz = in->shm_segsz;
- out.shm_atime = in->shm_atime;
- out.shm_dtime = in->shm_dtime;
- out.shm_ctime = in->shm_ctime;
- out.shm_cpid = in->shm_cpid;
- out.shm_lpid = in->shm_lpid;
- out.shm_nattch = in->shm_nattch;

return copy_to_user(buf, &out, sizeof(out));
}
--
1.7.1

--
Kees Cook
Ubuntu Security Team