smack: do not dereference NULL ipc object
In the SYSV ipc msgctl(),semctl(),shmctl() family, if the user passed *_INFO
as the desired operation, no specific object is meant to be controlled and
only system-wide information is returned. This leads to a NULL IPC object in
the LSM hooks if the _INFO flag is given.
Avoid dereferencing this NULL pointer in Smack ipc *ctl() methods.
Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 0241fd35..38d7075 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -1508,7 +1508,7 @@
*/
static int smack_shm_shmctl(struct shmid_kernel *shp, int cmd)
{
- char *ssp = smack_of_shm(shp);
+ char *ssp;
int may;
switch (cmd) {
@@ -1532,6 +1532,7 @@
return -EINVAL;
}
+ ssp = smack_of_shm(shp);
return smk_curacc(ssp, may);
}
@@ -1616,7 +1617,7 @@
*/
static int smack_sem_semctl(struct sem_array *sma, int cmd)
{
- char *ssp = smack_of_sem(sma);
+ char *ssp;
int may;
switch (cmd) {
@@ -1645,6 +1646,7 @@
return -EINVAL;
}
+ ssp = smack_of_sem(sma);
return smk_curacc(ssp, may);
}
@@ -1730,7 +1732,7 @@
*/
static int smack_msg_queue_msgctl(struct msg_queue *msq, int cmd)
{
- char *msp = smack_of_msq(msq);
+ char *msp;
int may;
switch (cmd) {
@@ -1752,6 +1754,7 @@
return -EINVAL;
}
+ msp = smack_of_msq(msq);
return smk_curacc(msp, may);
}