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ipc/sem.c: avoid ipc_rcu_putref for failed ipc_addid()

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Loosely based on a patch from Kees Cook <keescook@chromium.org>:
 - id and retval can be merged
 - if ipc_addid() fails, then use call_rcu() directly.

The difference is that call_rcu is used for failed ipc_addid() calls, to
continue to guaranteed an rcu delay for security_sem_free().

Link: http://lkml.kernel.org/r/20170525185107.12869-14-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Manfred Spraul 2017-07-12 14:35:13 -07:00 committed by Linus Torvalds
parent c3f6fb6fe4
commit 2ec55f8024
1 changed files with 4 additions and 5 deletions
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9
ipc/sem.c
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@ -479,7 +479,6 @@ static struct sem_array *sem_alloc(size_t nsems)
*/
static int newary(struct ipc_namespace *ns, struct ipc_params *params)
{
int id;
int retval;
struct sem_array *sma;
key_t key = params->key;
@ -520,10 +519,10 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
sma->sem_nsems = nsems;
sma->sem_ctime = get_seconds();
id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
if (id < 0) {
ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
return id;
retval = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
if (retval < 0) {
call_rcu(&sma->sem_perm.rcu, sem_rcu_free);
return retval;
}
ns->used_sems += nsems;