lkml.org 
[lkml]   [2017]   [May]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 13/20] ipc/sem.c: Avoid ipc_rcu_putref for failed ipc_addid()
Date
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().

Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Kees Cook <keescook@chromium.org>
---
ipc/sem.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/ipc/sem.c b/ipc/sem.c
index 445a5b5..2b2ed56 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -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;

--
2.9.3
\
 
 \ /
  Last update: 2017-05-25 20:56    [W:0.193 / U:0.524 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site