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Subject[PATCH] ipc: explicitly clear stack memory in user structs
CVE-2010-4072

The old shm interface will leak a few bytes of stack contents. Explicitly
clear structure using memset instead of C99-style initialization in case
there are ever holes in the packing.

Cc: stable <stable@kernel.org>
Signed-off-by: Kees Cook <kees.cook@canonical.com>
---
This was originally sent as http://lkml.org/lkml/2010/10/6/486 but was
never taken into any tree.

---
ipc/shm.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/ipc/shm.c b/ipc/shm.c
index 52ed77e..f943b1e 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -473,6 +473,7 @@ 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;
@@ -524,6 +525,7 @@ static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminf
{
struct shminfo out;

+ memset(&out, 0, sizeof(out));
if(in->shmmax > INT_MAX)
out.shmmax = INT_MAX;
else
--
1.7.1
--
Kees Cook
Ubuntu Security Team


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