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authorAlan Cox <alan@redhat.com>2008-10-29 14:01:20 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2010-05-26 14:27:09 -0700
commit3f955fe683ffdda7fd68e0b61779001cb9b50011 (patch)
treeb226e5056dcd6defc352ffc5ec29b3dd7c091c49 /mm
parent0ce0dd4ec9890eefb7b656c74bc5256c60626a85 (diff)
nfsd: fix vm overcommit crash
commit 731572d39fcd3498702eda4600db4c43d51e0b26 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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 8b5aa8ecdfa0..f3e5bfecf7b5 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -178,7 +178,8 @@ 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 4bf76868150c..7122331aaed5 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1432,7 +1432,8 @@ 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 04fb4f1ab88e..c088da12059f 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -163,8 +163,8 @@ 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)
@@ -181,8 +181,8 @@ 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)