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authorAlan Cox <alan@redhat.com>2008-10-29 17:01:20 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-30 14:38:47 -0400
commit731572d39fcd3498702eda4600db4c43d51e0b26 (patch)
treef892907ae20539845f353d72d2a2bf202b67e007
parent6c89161b10f5771ee0b51ada0fce0e8835e72ade (diff)
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>
-rw-r--r--include/linux/security.h6
-rw-r--r--mm/mmap.c3
-rw-r--r--mm/nommu.c3
-rw-r--r--mm/shmem.c8
-rw-r--r--security/security.c9
5 files changed, 23 insertions, 6 deletions
diff --git a/include/linux/security.h b/include/linux/security.h
index f5c4a51eb42e..c13f1cec9abb 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1585,6 +1585,7 @@ int security_syslog(int type);
1585int security_settime(struct timespec *ts, struct timezone *tz); 1585int security_settime(struct timespec *ts, struct timezone *tz);
1586int security_vm_enough_memory(long pages); 1586int security_vm_enough_memory(long pages);
1587int security_vm_enough_memory_mm(struct mm_struct *mm, long pages); 1587int security_vm_enough_memory_mm(struct mm_struct *mm, long pages);
1588int security_vm_enough_memory_kern(long pages);
1588int security_bprm_alloc(struct linux_binprm *bprm); 1589int security_bprm_alloc(struct linux_binprm *bprm);
1589void security_bprm_free(struct linux_binprm *bprm); 1590void security_bprm_free(struct linux_binprm *bprm);
1590void security_bprm_apply_creds(struct linux_binprm *bprm, int unsafe); 1591void security_bprm_apply_creds(struct linux_binprm *bprm, int unsafe);
@@ -1820,6 +1821,11 @@ static inline int security_vm_enough_memory(long pages)
1820 return cap_vm_enough_memory(current->mm, pages); 1821 return cap_vm_enough_memory(current->mm, pages);
1821} 1822}
1822 1823
1824static inline int security_vm_enough_memory_kern(long pages)
1825{
1826 return cap_vm_enough_memory(current->mm, pages);
1827}
1828
1823static inline int security_vm_enough_memory_mm(struct mm_struct *mm, long pages) 1829static inline int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
1824{ 1830{
1825 return cap_vm_enough_memory(mm, pages); 1831 return cap_vm_enough_memory(mm, pages);
diff --git a/mm/mmap.c b/mm/mmap.c
index 74f4d158022e..de14ac21e5b5 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)
175 175
176 /* Don't let a single process grow too big: 176 /* Don't let a single process grow too big:
177 leave 3% of the size of this process for other processes */ 177 leave 3% of the size of this process for other processes */
178 allowed -= mm->total_vm / 32; 178 if (mm)
179 allowed -= mm->total_vm / 32;
179 180
180 /* 181 /*
181 * cast `allowed' as a signed long because vm_committed_space 182 * cast `allowed' as a signed long because vm_committed_space
diff --git a/mm/nommu.c b/mm/nommu.c
index 2696b24f2bb3..7695dc850785 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)
1454 1454
1455 /* Don't let a single process grow too big: 1455 /* Don't let a single process grow too big:
1456 leave 3% of the size of this process for other processes */ 1456 leave 3% of the size of this process for other processes */
1457 allowed -= current->mm->total_vm / 32; 1457 if (mm)
1458 allowed -= mm->total_vm / 32;
1458 1459
1459 /* 1460 /*
1460 * cast `allowed' as a signed long because vm_committed_space 1461 * cast `allowed' as a signed long because vm_committed_space
diff --git a/mm/shmem.c b/mm/shmem.c
index d38d7e61fcd0..0ed075215e5f 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)
161 */ 161 */
162static inline int shmem_acct_size(unsigned long flags, loff_t size) 162static inline int shmem_acct_size(unsigned long flags, loff_t size)
163{ 163{
164 return (flags & VM_ACCOUNT)? 164 return (flags & VM_ACCOUNT) ?
165 security_vm_enough_memory(VM_ACCT(size)): 0; 165 security_vm_enough_memory_kern(VM_ACCT(size)) : 0;
166} 166}
167 167
168static inline void shmem_unacct_size(unsigned long flags, loff_t size) 168static 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)
179 */ 179 */
180static inline int shmem_acct_block(unsigned long flags) 180static inline int shmem_acct_block(unsigned long flags)
181{ 181{
182 return (flags & VM_ACCOUNT)? 182 return (flags & VM_ACCOUNT) ?
183 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 183 0 : security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE));
184} 184}
185 185
186static inline void shmem_unacct_blocks(unsigned long flags, long pages) 186static inline void shmem_unacct_blocks(unsigned long flags, long pages)
diff --git a/security/security.c b/security/security.c
index 255b08559b2b..c0acfa7177e5 100644
--- a/security/security.c
+++ b/security/security.c
@@ -198,14 +198,23 @@ int security_settime(struct timespec *ts, struct timezone *tz)
198 198
199int security_vm_enough_memory(long pages) 199int security_vm_enough_memory(long pages)
200{ 200{
201 WARN_ON(current->mm == NULL);
201 return security_ops->vm_enough_memory(current->mm, pages); 202 return security_ops->vm_enough_memory(current->mm, pages);
202} 203}
203 204
204int security_vm_enough_memory_mm(struct mm_struct *mm, long pages) 205int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
205{ 206{
207 WARN_ON(mm == NULL);
206 return security_ops->vm_enough_memory(mm, pages); 208 return security_ops->vm_enough_memory(mm, pages);
207} 209}
208 210
211int security_vm_enough_memory_kern(long pages)
212{
213 /* If current->mm is a kernel thread then we will pass NULL,
214 for this specific case that is fine */
215 return security_ops->vm_enough_memory(current->mm, pages);
216}
217
209int security_bprm_alloc(struct linux_binprm *bprm) 218int security_bprm_alloc(struct linux_binprm *bprm)
210{ 219{
211 return security_ops->bprm_alloc_security(bprm); 220 return security_ops->bprm_alloc_security(bprm);