nfsd: fix vm overcommit crash
Junjiro R. Okajima reported a problem where knfsd crashes if you are
using it to export shmemfs objects and run strict overcommit. In this
situation the current->mm based modifier to the overcommit goes through a
NULL pointer.
We could simply check for NULL and skip the modifier but we've caught
other real bugs in the past from mm being NULL here - cases where we did
need a valid mm set up (eg the exec bug about a year ago).
To preserve the checks and get the logic we want shuffle the checking
around and add a new helper to the vm_ security wrappers
Also fix a current->mm reference in nommu that should use the passed mm
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix build]
Reported-by: Junjiro R. Okajima <hooanon05@yahoo.co.jp>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/security.h b/include/linux/security.h
index f5c4a51..c13f1ce 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1585,6 +1585,7 @@
int security_settime(struct timespec *ts, struct timezone *tz);
int security_vm_enough_memory(long pages);
int security_vm_enough_memory_mm(struct mm_struct *mm, long pages);
+int security_vm_enough_memory_kern(long pages);
int security_bprm_alloc(struct linux_binprm *bprm);
void security_bprm_free(struct linux_binprm *bprm);
void security_bprm_apply_creds(struct linux_binprm *bprm, int unsafe);
@@ -1820,6 +1821,11 @@
return cap_vm_enough_memory(current->mm, pages);
}
+static inline int security_vm_enough_memory_kern(long pages)
+{
+ return cap_vm_enough_memory(current->mm, pages);
+}
+
static inline int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
{
return cap_vm_enough_memory(mm, pages);