lkml.org 
[lkml]   [2012]   [Jan]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/2] Staging: android: binder: Add some error checks
Date
- 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>
---
drivers/staging/android/binder.c | 12 +++++++++++-
1 files changed, 11 insertions(+), 1 deletions(-)
diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c
index 7491801..846b429 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)
@@ -2803,6 +2809,7 @@ 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";
@@ -2817,6 +2824,7 @@ 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()) {
@@ -2849,7 +2857,7 @@ 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",
@@ -2860,10 +2868,12 @@ 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);
--
1.7.7.3
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2012-01-21 04:59    [from the cache]
©2003-2011 Jasper Spaans