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authorAlan Cox <alan@redhat.com>2008-10-29 14:01:20 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-30 11:38:47 -0700
commit731572d39fcd3498702eda4600db4c43d51e0b26 (patch)
treef892907ae20539845f353d72d2a2bf202b67e007 /mm/nommu.c
parent6c89161b10f5771ee0b51ada0fce0e8835e72ade (diff)
downloadvexpress-lsk-731572d39fcd3498702eda4600db4c43d51e0b26.tar.gz
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>
Diffstat (limited to 'mm/nommu.c')
-rw-r--r--mm/nommu.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/nommu.c b/mm/nommu.c
index 2696b24f2bb..7695dc85078 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1454,7 +1454,8 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
/* Don't let a single process grow too big:
leave 3% of the size of this process for other processes */
- allowed -= current->mm->total_vm / 32;
+ if (mm)
+ allowed -= mm->total_vm / 32;
/*
* cast `allowed' as a signed long because vm_committed_space