lkml.org 
[lkml]   [2012]   [Dec]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] omap_vout: find_vma() needs ->mmap_sem held

Walking rbtree while it's modified is a Bad Idea(tm); besides,
the result of find_vma() can be freed just as it's getting returned
to caller. Fortunately, it's easy to fix - just take ->mmap_sem a bit
earlier (and don't bother with find_vma() at all if virtp >= PAGE_OFFSET -
in that case we don't even look at its result).

Cc: stable@vger.kernel.org [2.6.35]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
diff --git a/drivers/media/platform/omap/omap_vout.c b/drivers/media/platform/omap/omap_vout.c
index 9935040..984512f 100644
--- a/drivers/media/platform/omap/omap_vout.c
+++ b/drivers/media/platform/omap/omap_vout.c
@@ -207,19 +207,21 @@ static u32 omap_vout_uservirt_to_phys(u32 virtp)
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;

- vma = find_vma(mm, virtp);
/* For kernel direct-mapped memory, take the easy way */
- if (virtp >= PAGE_OFFSET) {
- physp = virt_to_phys((void *) virtp);
+ if (virtp >= PAGE_OFFSET)
+ return virt_to_phys((void *) virtp);
+
+ down_read(&current->mm->mmap_sem);
+ vma = find_vma(mm, virtp);
} else if (vma && (vma->vm_flags & VM_IO) && vma->vm_pgoff) {
/* this will catch, kernel-allocated, mmaped-to-usermode
addresses */
physp = (vma->vm_pgoff << PAGE_SHIFT) + (virtp - vma->vm_start);
+ up_read(&current->mm->mmap_sem);
} else {
/* otherwise, use get_user_pages() for general userland pages */
int res, nr_pages = 1;
struct page *pages;
- down_read(&current->mm->mmap_sem);

res = get_user_pages(current, current->mm, virtp, nr_pages, 1,
0, &pages, NULL);

\
 
 \ /
  Last update: 2012-12-15 21:41    [W:0.077 / U:5.988 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site