The patch titled
Subject: ipc/sem.c: avoid ipc_rcu_putref for failed ipc_addid()
has been added to the -mm tree. Its filename is
ipc-semc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipc-semc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipc-semc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
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------------------------------------------------------
From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Subject: ipc/sem.c: avoid ipc_rcu_putref for failed ipc_addid()
Loosely based on a patch from Kees Cook <keescook@xxxxxxxxxxxx>:
- 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@xxxxxxxxxxxxxxxx
Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/sem.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff -puN ipc/sem.c~ipc-semc-avoid-ipc_rcu_putref-for-failed-ipc_addid ipc/sem.c
--- a/ipc/sem.c~ipc-semc-avoid-ipc_rcu_putref-for-failed-ipc_addid
+++ a/ipc/sem.c
@@ -479,7 +479,6 @@ static struct sem_array *sem_alloc(size_
*/
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 *
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;
_
Patches currently in -mm which might be from manfred@xxxxxxxxxxxxxxxx are
ipc-semc-remove-sem_base-embed-struct-sem.patch
ipc-semc-remove-sem_base-embed-struct-sem-v3.patch
ipc-merge-ipc_rcu-and-kern_ipc_perm.patch
include-linux-semh-correctly-document-sem_ctime.patch
ipc-semc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
ipc-shmc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
ipc-msgc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
ipc-utilh-update-documentation-for-ipc_getref-and-ipc_putref.patch
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