Comments
Patch
@@ -206,19 +206,21 @@ 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);
- } else if (vma && (vma->vm_flags & VM_IO) && vma->vm_pgoff) {
+ if (virtp >= PAGE_OFFSET)
+ return virt_to_phys((void *) virtp);
+
+ down_read(¤t->mm->mmap_sem);
+ vma = find_vma(mm, virtp);
+ 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(¤t->mm->mmap_sem);
} else {
/* otherwise, use get_user_pages() for general userland pages */
int res, nr_pages = 1;
struct page *pages;
- down_read(¤t->mm->mmap_sem);
res = get_user_pages(current, current->mm, virtp, nr_pages, 1,
0, &pages, NULL);
This is a note to let you know that I have just added a patch titled omap_vout: find_vma() needs ->mmap_sem held to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From cd668258395925e3b35853831a31e6392907532c Mon Sep 17 00:00:00 2001 From: Al Viro <viro@ZenIV.linux.org.uk> Date: Sun, 16 Dec 2012 16:04:46 -0300 Subject: [PATCH] omap_vout: find_vma() needs ->mmap_sem held commit 55ee64b30a38d688232e5eb2860467dddc493573 upstream. 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). While we are at it, what prevents VIDIOC_PREPARE_BUF calling v4l_prepare_buf() -> (e.g) vb2_ioctl_prepare_buf() -> vb2_prepare_buf() -> __buf_prepare() -> __qbuf_userptr() -> vb2_vmalloc_get_userptr() -> find_vma(), AFAICS without having taken ->mmap_sem anywhere in process? The code flow is bloody convoluted and depends on a bunch of things done by initialization, so I certainly might've missed something... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Sakari Ailus <sakari.ailus@iki.fi> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: Archit Taneja <archit@ti.com> Cc: Prabhakar Lad <prabhakar.lad@ti.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/media/video/omap/omap_vout.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) -- 1.8.1.2