Commit a2642f87 authored by Manfred Spraul's avatar Manfred Spraul Committed by Linus Torvalds

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

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

The difference is that call_rcu is used for failures after
security_shm_alloc(), to continue to guaranteed an rcu delay for
security_sem_free().

Link: http://lkml.kernel.org/r/20170525185107.12869-15-manfred@colorfullife.comSigned-off-by: default avatarManfred Spraul <manfred@colorfullife.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2ec55f80
...@@ -548,7 +548,6 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) ...@@ -548,7 +548,6 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
struct file *file; struct file *file;
char name[13]; char name[13];
int id;
vm_flags_t acctflag = 0; vm_flags_t acctflag = 0;
if (size < SHMMIN || size > ns->shm_ctlmax) if (size < SHMMIN || size > ns->shm_ctlmax)
...@@ -617,11 +616,9 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) ...@@ -617,11 +616,9 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
shp->shm_file = file; shp->shm_file = file;
shp->shm_creator = current; shp->shm_creator = current;
id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni); error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
if (id < 0) { if (error < 0)
error = id;
goto no_id; goto no_id;
}
list_add(&shp->shm_clist, &current->sysvshm.shm_clist); list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
...@@ -643,7 +640,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) ...@@ -643,7 +640,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
user_shm_unlock(size, shp->mlock_user); user_shm_unlock(size, shp->mlock_user);
fput(file); fput(file);
no_file: no_file:
ipc_rcu_putref(&shp->shm_perm, shm_rcu_free); call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
return error; return error;
} }
......
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