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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
parent6c89161b10f5771ee0b51ada0fce0e8835e72ade (diff)
downloadop-kernel-dev-731572d39fcd3498702eda4600db4c43d51e0b26.zip
op-kernel-dev-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')
-rw-r--r--mm/mmap.c3
-rw-r--r--mm/nommu.c3
-rw-r--r--mm/shmem.c8
3 files changed, 8 insertions, 6 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 74f4d15..de14ac2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -175,7 +175,8 @@ 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 -= mm->total_vm / 32;
+ if (mm)
+ allowed -= mm->total_vm / 32;
/*
* cast `allowed' as a signed long because vm_committed_space
diff --git a/mm/nommu.c b/mm/nommu.c
index 2696b24..7695dc8 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
diff --git a/mm/shmem.c b/mm/shmem.c
index d38d7e6..0ed0752 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -161,8 +161,8 @@ static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
*/
static inline int shmem_acct_size(unsigned long flags, loff_t size)
{
- return (flags & VM_ACCOUNT)?
- security_vm_enough_memory(VM_ACCT(size)): 0;
+ return (flags & VM_ACCOUNT) ?
+ security_vm_enough_memory_kern(VM_ACCT(size)) : 0;
}
static inline void shmem_unacct_size(unsigned long flags, loff_t size)
@@ -179,8 +179,8 @@ static inline void shmem_unacct_size(unsigned long flags, loff_t size)
*/
static inline int shmem_acct_block(unsigned long flags)
{
- return (flags & VM_ACCOUNT)?
- 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
+ return (flags & VM_ACCOUNT) ?
+ 0 : security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE));
}
static inline void shmem_unacct_blocks(unsigned long flags, long pages)
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