fs, proc: fix ABBA deadlock in case of execution attempt of map_files/ entries

[linux-flexiantxendom0-3.2.10.git] / fs / proc / base.c

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 1c8b280..8e139c9 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2177,16 +2177,16 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
                goto out;
 
        result = ERR_PTR(-EACCES);
-       if (lock_trace(task))
+       if (!ptrace_may_access(task, PTRACE_MODE_READ))
                goto out_put_task;
 
        result = ERR_PTR(-ENOENT);
        if (dname_to_vma_addr(dentry, &vm_start, &vm_end))
-               goto out_unlock;
+               goto out_put_task;
 
        mm = get_task_mm(task);
        if (!mm)
-               goto out_unlock;
+               goto out_put_task;
 
        down_read(&mm->mmap_sem);
        vma = find_exact_vma(mm, vm_start, vm_end);
@@ -2198,8 +2198,6 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 out_no_vma:
        up_read(&mm->mmap_sem);
        mmput(mm);
-out_unlock:
-       unlock_trace(task);
 out_put_task:
        put_task_struct(task);
 out:
@@ -2233,7 +2231,7 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
                goto out;
 
        ret = -EACCES;
-       if (lock_trace(task))
+       if (!ptrace_may_access(task, PTRACE_MODE_READ))
                goto out_put_task;
 
        ret = 0;
@@ -2241,12 +2239,12 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
        case 0:
                ino = inode->i_ino;
                if (filldir(dirent, ".", 1, 0, ino, DT_DIR) < 0)
-                       goto out_unlock;
+                       goto out_put_task;
                filp->f_pos++;
        case 1:
                ino = parent_ino(dentry);
                if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
-                       goto out_unlock;
+                       goto out_put_task;
                filp->f_pos++;
        default:
        {
@@ -2257,7 +2255,7 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
 
                mm = get_task_mm(task);
                if (!mm)
-                       goto out_unlock;
+                       goto out_put_task;
                down_read(&mm->mmap_sem);
 
                nr_files = 0;
@@ -2287,7 +2285,7 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
                                        flex_array_free(fa);
                                up_read(&mm->mmap_sem);
                                mmput(mm);
-                               goto out_unlock;
+                               goto out_put_task;
                        }
                        for (i = 0, vma = mm->mmap, pos = 2; vma;
                                        vma = vma->vm_next) {
@@ -2332,8 +2330,6 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
        }
        }
 
-out_unlock:
-       unlock_trace(task);
 out_put_task:
        put_task_struct(task);
 out: