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-rw-r--r--include/linux/shm.h3
-rw-r--r--ipc/shm.c27
2 files changed, 23 insertions, 7 deletions
diff --git a/include/linux/shm.h b/include/linux/shm.h
index 7d27ffd..92808b8 100644
--- a/include/linux/shm.h
+++ b/include/linux/shm.h
@@ -95,6 +95,9 @@ struct shmid_kernel /* private to the kernel */
pid_t shm_cprid;
pid_t shm_lprid;
struct user_struct *mlock_user;
+
+ /* The task created the shm object. NULL if the task is dead. */
+ struct task_struct *shm_creator;
};
/* shm_mode upper byte flags */
diff --git a/ipc/shm.c b/ipc/shm.c
index 3f5b143..fdaf8be 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -239,7 +239,23 @@ static int shm_try_destroy_current(int id, void *p, void *data)
if (IS_ERR(shp))
return 0;
- if (shp->shm_cprid != task_tgid_vnr(current)) {
+ if (shp->shm_creator != current) {
+ shm_unlock(shp);
+ return 0;
+ }
+
+ /*
+ * Mark it as orphaned to destroy the segment when
+ * kernel.shm_rmid_forced is changed.
+ * It is noop if the following shm_may_destroy() returns true.
+ */
+ shp->shm_creator = NULL;
+
+ /*
+ * Don't even try to destroy it. If shm_rmid_forced=0 and IPC_RMID
+ * is not set, it shouldn't be deleted here.
+ */
+ if (!ns->shm_rmid_forced) {
shm_unlock(shp);
return 0;
}
@@ -255,7 +271,6 @@ static int shm_try_destroy_orphaned(int id, void *p, void *data)
{
struct ipc_namespace *ns = data;
struct shmid_kernel *shp = shm_lock(ns, id);
- struct task_struct *task;
if (IS_ERR(shp))
return 0;
@@ -263,11 +278,8 @@ static int shm_try_destroy_orphaned(int id, void *p, void *data)
/*
* We want to destroy segments without users and with already
* exit'ed originating process.
- *
- * XXX: the originating process may exist in another pid namespace.
*/
- task = find_task_by_vpid(shp->shm_cprid);
- if (task != NULL) {
+ if (shp->shm_creator != NULL) {
shm_unlock(shp);
return 0;
}
@@ -295,7 +307,7 @@ void exit_shm(struct task_struct *task)
if (!nsp)
return;
ns = nsp->ipc_ns;
- if (!ns || !ns->shm_rmid_forced)
+ if (!ns)
return;
/* Destroy all already created segments, but not mapped yet */
@@ -494,6 +506,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
shp->shm_segsz = size;
shp->shm_nattch = 0;
shp->shm_file = file;
+ shp->shm_creator = current;
/*
* shmid gets reported as "inode#" in /proc/pid/maps.
* proc-ps tools use this. Changing this will break them.
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