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Commit fb39380b authored by Marcelo Tosatti's avatar Marcelo Tosatti Committed by Linus Torvalds
Browse files

pagemap: proper read error handling 



Fix pagemap_read() error handling by releasing acquired resources and checking
for get_user_pages() partial failure.

Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Acked-by: default avatarMatt Mackall <mpm@selenic.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b500ce8d

fs/proc/task_mmu.c

+13 −5
Original line number Diff line number Diff line
@@ -640,17 +640,17 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, 


	ret = -EACCES;

	if (!ptrace_may_attach(task))

		goto out;

		goto out_task;



	ret = -EINVAL;

	/* file position must be aligned */

	if (*ppos % PM_ENTRY_BYTES)

		goto out;

		goto out_task;



	ret = 0;

	mm = get_task_mm(task);

	if (!mm)

		goto out;

		goto out_task;



	ret = -ENOMEM;

	uaddr = (unsigned long)buf & PAGE_MASK;
@@ -658,7 +658,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, 
	pagecount = (PAGE_ALIGN(uend) - uaddr) / PAGE_SIZE;

	pages = kmalloc(pagecount * sizeof(struct page *), GFP_KERNEL);

	if (!pages)

		goto out_task;

		goto out_mm;



	down_read(&current->mm->mmap_sem);

	ret = get_user_pages(current, current->mm, uaddr, pagecount,
@@ -668,6 +668,12 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, 
	if (ret < 0)

		goto out_free;



	if (ret != pagecount) {

		pagecount = ret;

		ret = -EFAULT;

		goto out_pages;

	}



	pm.out = buf;

	pm.end = buf + count;
@@ -699,15 +705,17 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, 
			ret = pm.out - buf;

	}



out_pages:

	for (; pagecount; pagecount--) {

		page = pages[pagecount-1];

		if (!PageReserved(page))

			SetPageDirty(page);

		page_cache_release(page);

	}

	mmput(mm);

out_free:

	kfree(pages);

out_mm:

	mmput(mm);

out_task:

	put_task_struct(task);

out: