The patch titled nfsd: fix vm overcommit crash has been removed from the -mm tree. Its filename was nfsd-fix-vm-overcommit-crash.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: nfsd: fix vm overcommit crash From: Alan Cox <alan@xxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxx: coding-style fixes] [akpm@xxxxxxxxxxxxxxxxxxxx: fix build] Reported-by: Junjiro R. Okajima <hooanon05@xxxxxxxxxxx> Acked-by: James Morris <jmorris@xxxxxxxxx> Signed-off-by: Alan Cox <alan@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/security.h | 6 ++++++ mm/mmap.c | 3 ++- mm/nommu.c | 3 ++- mm/shmem.c | 8 ++++---- security/security.c | 9 +++++++++ 5 files changed, 23 insertions(+), 6 deletions(-) diff -puN include/linux/security.h~nfsd-fix-vm-overcommit-crash include/linux/security.h --- a/include/linux/security.h~nfsd-fix-vm-overcommit-crash +++ a/include/linux/security.h @@ -1585,6 +1585,7 @@ int security_syslog(int type); 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 @@ static inline int security_vm_enough_mem 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); diff -puN mm/mmap.c~nfsd-fix-vm-overcommit-crash mm/mmap.c --- a/mm/mmap.c~nfsd-fix-vm-overcommit-crash +++ a/mm/mmap.c @@ -175,7 +175,8 @@ int __vm_enough_memory(struct mm_struct /* 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 -puN mm/nommu.c~nfsd-fix-vm-overcommit-crash mm/nommu.c --- a/mm/nommu.c~nfsd-fix-vm-overcommit-crash +++ a/mm/nommu.c @@ -1454,7 +1454,8 @@ int __vm_enough_memory(struct mm_struct /* 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 -puN mm/shmem.c~nfsd-fix-vm-overcommit-crash mm/shmem.c --- a/mm/shmem.c~nfsd-fix-vm-overcommit-crash +++ a/mm/shmem.c @@ -161,8 +161,8 @@ static inline struct shmem_sb_info *SHME */ 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(uns */ 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) diff -puN security/security.c~nfsd-fix-vm-overcommit-crash security/security.c --- a/security/security.c~nfsd-fix-vm-overcommit-crash +++ a/security/security.c @@ -198,14 +198,23 @@ int security_settime(struct timespec *ts int security_vm_enough_memory(long pages) { + WARN_ON(current->mm == NULL); return security_ops->vm_enough_memory(current->mm, pages); } int security_vm_enough_memory_mm(struct mm_struct *mm, long pages) { + WARN_ON(mm == NULL); return security_ops->vm_enough_memory(mm, pages); } +int security_vm_enough_memory_kern(long pages) +{ + /* If current->mm is a kernel thread then we will pass NULL, + for this specific case that is fine */ + return security_ops->vm_enough_memory(current->mm, pages); +} + int security_bprm_alloc(struct linux_binprm *bprm) { return security_ops->bprm_alloc_security(bprm); _ Patches currently in -mm which might be from alan@xxxxxxxxxx are linux-next.patch blackfin-remove-__function__-in-new-serial-driver.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html