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authorJames Morris <jmorris@namei.org>2009-06-11 11:03:14 +1000
committerJames Morris <jmorris@namei.org>2009-06-11 11:03:14 +1000
commit73fbad283cfbbcf02939bdbda31fc4a30e729cca (patch)
tree7c89fe13e1b4a2c7f2d60f4ea6eaf69c14bccab7 /mm
parent769f3e8c384795cc350e2aae27de2a12374d19d4 (diff)
parent35f2c2f6f6ae13ef23c4f68e6d3073753077ca43 (diff)
Merge branch 'next' into for-linus
Diffstat (limited to 'mm')
-rw-r--r--mm/Kconfig19
-rw-r--r--mm/mmap.c3
-rw-r--r--mm/nommu.c3
-rw-r--r--mm/shmem.c2
4 files changed, 26 insertions, 1 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index c2b57d81e15..71830ba7b98 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -226,6 +226,25 @@ config HAVE_MLOCKED_PAGE_BIT
config MMU_NOTIFIER
bool
+config DEFAULT_MMAP_MIN_ADDR
+ int "Low address space to protect from user allocation"
+ default 4096
+ help
+ This is the portion of low virtual memory which should be protected
+ from userspace allocation. Keeping a user from writing to low pages
+ can help reduce the impact of kernel NULL pointer bugs.
+
+ For most ia64, ppc64 and x86 users with lots of address space
+ a value of 65536 is reasonable and should cause no problems.
+ On arm and other archs it should not be higher than 32768.
+ Programs which use vm86 functionality would either need additional
+ permissions from either the LSM or the capabilities module or have
+ this protection disabled.
+
+ This value can be changed after boot using the
+ /proc/sys/vm/mmap_min_addr tunable.
+
+
config NOMMU_INITIAL_TRIM_EXCESS
int "Turn on mmap() excess space trimming before booting"
depends on !MMU
diff --git a/mm/mmap.c b/mm/mmap.c
index 6b7b1a95944..2b43fa1aa3c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -87,6 +87,9 @@ int sysctl_overcommit_ratio = 50; /* default is 50% */
int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
struct percpu_counter vm_committed_as;
+/* amount of vm to protect from userspace access */
+unsigned long mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR;
+
/*
* Check that a process has enough memory to allocate a new virtual
* mapping. 0 means there is enough memory for the allocation to
diff --git a/mm/nommu.c b/mm/nommu.c
index b571ef70742..2fd2ad5da98 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -69,6 +69,9 @@ int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
int heap_stack_gap = 0;
+/* amount of vm to protect from userspace access */
+unsigned long mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR;
+
atomic_long_t mmap_pages_allocated;
EXPORT_SYMBOL(mem_map);
diff --git a/mm/shmem.c b/mm/shmem.c
index b25f95ce3db..0132fbd45a2 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2659,6 +2659,7 @@ struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
if (error)
goto close_file;
#endif
+ ima_counts_get(file);
return file;
close_file:
@@ -2684,7 +2685,6 @@ int shmem_zero_setup(struct vm_area_struct *vma)
if (IS_ERR(file))
return PTR_ERR(file);
- ima_shm_check(file);
if (vma->vm_file)
fput(vma->vm_file);
vma->vm_file = file;