diff options
| -rw-r--r-- | fs/proc/base.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 49b82beec318..22794e8ab996 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -775,6 +775,13 @@ static int mem_open(struct inode* inode, struct file* file) if (IS_ERR(mm)) return PTR_ERR(mm); + if (mm) { + /* ensure this mm_struct can't be freed */ + atomic_inc(&mm->mm_count); + /* but do not pin its memory */ + mmput(mm); + } + /* OK to pass negative loff_t, we can catch out-of-range */ file->f_mode |= FMODE_UNSIGNED_OFFSET; file->private_data = mm; @@ -798,6 +805,9 @@ static ssize_t mem_rw(struct file *file, char __user *buf, return -ENOMEM; copied = 0; + if (!atomic_inc_not_zero(&mm->mm_users)) + goto free; + while (count > 0) { int this_len = min_t(int, count, PAGE_SIZE); @@ -825,6 +835,8 @@ static ssize_t mem_rw(struct file *file, char __user *buf, } *ppos = addr; + mmput(mm); +free: free_page((unsigned long) page); return copied; } @@ -861,7 +873,7 @@ static int mem_release(struct inode *inode, struct file *file) { struct mm_struct *mm = file->private_data; if (mm) - mmput(mm); + mmdrop(mm); return 0; } |