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authorArve Hjønnevåg <arve@android.com>2012-02-01 15:29:13 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-02-08 14:14:13 -0800
commitbd1eff9741af27378b241b347041c724bb28e857 (patch)
tree47ec1db37ae76c3b8b4b2908cc6a5129191b5089 /drivers
parentb0d017e80e9f4e6b37e699b9a944646e64deb473 (diff)
Staging: android: binder: Fix crashes when sharing a binder file between processes
Opening the binder driver and sharing the file returned with other processes (e.g. by calling fork) can crash the kernel. Prevent these crashes with the following changes: - Add a mutex to protect against two processes mmapping the same binder_proc. - After locking mmap_sem, check that the vma we want to access (still) points to the same mm_struct. - Use proc->tsk instead of current to get the files struct since this is where we get the rlimit from. Signed-off-by: Arve Hjønnevåg <arve@android.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/staging/android/binder.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c
index 48cf27cdb51..f0b7e6605ab 100644
--- a/drivers/staging/android/binder.c
+++ b/drivers/staging/android/binder.c
@@ -38,6 +38,7 @@
static DEFINE_MUTEX(binder_lock);
static DEFINE_MUTEX(binder_deferred_lock);
+static DEFINE_MUTEX(binder_mmap_lock);
static HLIST_HEAD(binder_procs);
static HLIST_HEAD(binder_deferred_list);
@@ -632,6 +633,11 @@ static int binder_update_page_range(struct binder_proc *proc, int allocate,
if (mm) {
down_write(&mm->mmap_sem);
vma = proc->vma;
+ if (vma && mm != vma->vm_mm) {
+ pr_err("binder: %d: vma mm and task mm mismatch\n",
+ proc->pid);
+ vma = NULL;
+ }
}
if (allocate == 0)
@@ -2802,6 +2808,7 @@ static int binder_mmap(struct file *filp, struct vm_area_struct *vma)
}
vma->vm_flags = (vma->vm_flags | VM_DONTCOPY) & ~VM_MAYWRITE;
+ mutex_lock(&binder_mmap_lock);
if (proc->buffer) {
ret = -EBUSY;
failure_string = "already mapped";
@@ -2816,6 +2823,7 @@ static int binder_mmap(struct file *filp, struct vm_area_struct *vma)
}
proc->buffer = area->addr;
proc->user_buffer_offset = vma->vm_start - (uintptr_t)proc->buffer;
+ mutex_unlock(&binder_mmap_lock);
#ifdef CONFIG_CPU_CACHE_VIPT
if (cache_is_vipt_aliasing()) {
@@ -2848,7 +2856,7 @@ static int binder_mmap(struct file *filp, struct vm_area_struct *vma)
binder_insert_free_buffer(proc, buffer);
proc->free_async_space = proc->buffer_size / 2;
barrier();
- proc->files = get_files_struct(current);
+ proc->files = get_files_struct(proc->tsk);
proc->vma = vma;
/*printk(KERN_INFO "binder_mmap: %d %lx-%lx maps %p\n",
@@ -2859,10 +2867,12 @@ err_alloc_small_buf_failed:
kfree(proc->pages);
proc->pages = NULL;
err_alloc_pages_failed:
+ mutex_lock(&binder_mmap_lock);
vfree(proc->buffer);
proc->buffer = NULL;
err_get_vm_area_failed:
err_already_mapped:
+ mutex_unlock(&binder_mmap_lock);
err_bad_arg:
printk(KERN_ERR "binder_mmap: %d %lx-%lx %s failed %d\n",
proc->pid, vma->vm_start, vma->vm_end, failure_string, ret);