Re: [PATCH 3.4-stable][CVE] Fix a few incorrectly checked [io_]remap_pfn_range() calls

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On Fri, Nov 22, 2013 at 01:26:38PM +0800, Li Zefan wrote:
> Hi Greg,
> 
> Please queue this for 3.4 stable kernel.
> 
> It fixes a CVE bug (http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2013-6763&cid=4),
> and kernels >= 3.0 are affected. The fix has been backported to 3.8,
> 3.10 and 3.11.
> 
> I found you backported 4 patches in order to apply the fix to 3.10. As
> they're not necessary but to resolve conflicts, and there're 2 more
> conflicts in 3.4-stable, I just adjusted the context.
> 
> The au1100fb.c and au1200fb.c parts were not build-tested, because
> they depend on CONFIG_MIPS_ALCHEMY.
> 
> =======================
> 
> From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Date: Fri, 22 Nov 2013 12:32:21 +0800
> Subject: [PATCH] Fix a few incorrectly checked [io_]remap_pfn_range() calls
> 
> commit 7314e613d5ff9f0934f7a0f74ed7973b903315d1 upstream.
> 
> Nico Golde reports a few straggling uses of [io_]remap_pfn_range() that
> really should use the vm_iomap_memory() helper.  This trivially converts
> two of them to the helper, and comments about why the third one really
> needs to continue to use remap_pfn_range(), and adds the missing size
> check.
> 
> Reported-by: Nico Golde <nico@xxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx.
> [lizf: backported to 3.4:
>  - adjust context
>  - no uio_physical_vm_ops]
> Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
> ---
>  drivers/uio/uio.c        | 16 +++++++++++++++-
>  drivers/video/au1100fb.c | 26 +-------------------------
>  drivers/video/au1200fb.c | 23 +----------------------
>  3 files changed, 17 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index a783d53..7150752 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -650,16 +650,30 @@ static int uio_mmap_physical(struct vm_area_struct *vma)
>  {
>  	struct uio_device *idev = vma->vm_private_data;
>  	int mi = uio_find_mem_index(vma);
> +	struct uio_mem *mem;
>  	if (mi < 0)
>  		return -EINVAL;
> +	mem = idev->info->mem + mi;
> +
> +	if (vma->vm_end - vma->vm_start > mem->size)
> +		return -EINVAL;
>  
>  	vma->vm_flags |= VM_IO | VM_RESERVED;
>  
>  	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
>  
> +	/*
> +	 * We cannot use the vm_iomap_memory() helper here,
> +	 * because vma->vm_pgoff is the map index we looked
> +	 * up above in uio_find_mem_index(), rather than an
> +	 * actual page offset into the mmap.
> +	 *
> +	 * So we just do the physical mmap without a page
> +	 * offset.
> +	 */
>  	return remap_pfn_range(vma,
>  			       vma->vm_start,
> -			       idev->info->mem[mi].addr >> PAGE_SHIFT,
> +			       mem->addr >> PAGE_SHIFT,
>  			       vma->vm_end - vma->vm_start,
>  			       vma->vm_page_prot);
>  }
> diff --git a/drivers/video/au1100fb.c b/drivers/video/au1100fb.c
> index ffbce45..612c1c7 100644
> --- a/drivers/video/au1100fb.c
> +++ b/drivers/video/au1100fb.c
> @@ -375,39 +375,15 @@ void au1100fb_fb_rotate(struct fb_info *fbi, int angle)
>  int au1100fb_fb_mmap(struct fb_info *fbi, struct vm_area_struct *vma)
>  {
>  	struct au1100fb_device *fbdev;
> -	unsigned int len;
> -	unsigned long start=0, off;
>  
>  	fbdev = to_au1100fb_device(fbi);
>  
> -	if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT)) {
> -		return -EINVAL;
> -	}
> -
> -	start = fbdev->fb_phys & PAGE_MASK;
> -	len = PAGE_ALIGN((start & ~PAGE_MASK) + fbdev->fb_len);
> -
> -	off = vma->vm_pgoff << PAGE_SHIFT;
> -
> -	if ((vma->vm_end - vma->vm_start + off) > len) {
> -		return -EINVAL;
> -	}
> -
> -	off += start;
> -	vma->vm_pgoff = off >> PAGE_SHIFT;
> -
>  	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
>  	pgprot_val(vma->vm_page_prot) |= (6 << 9); //CCA=6
>  
>  	vma->vm_flags |= VM_IO;
>  
> -	if (io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
> -				vma->vm_end - vma->vm_start,
> -				vma->vm_page_prot)) {
> -		return -EAGAIN;
> -	}
> -
> -	return 0;
> +	return vm_iomap_memory(vma, fbdev->fb_phys, fbdev->fb_len);
>  }
>  
>  static struct fb_ops au1100fb_ops =
> diff --git a/drivers/video/au1200fb.c b/drivers/video/au1200fb.c
> index 7ca79f0..117be3d 100644
> --- a/drivers/video/au1200fb.c
> +++ b/drivers/video/au1200fb.c
> @@ -1233,36 +1233,15 @@ static int au1200fb_fb_blank(int blank_mode, struct fb_info *fbi)
>   * method mainly to allow the use of the TLB streaming flag (CCA=6)
>   */
>  static int au1200fb_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
> -
>  {
> -	unsigned int len;
> -	unsigned long start=0, off;
>  	struct au1200fb_device *fbdev = info->par;
>  
> -	if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT)) {
> -		return -EINVAL;
> -	}
> -
> -	start = fbdev->fb_phys & PAGE_MASK;
> -	len = PAGE_ALIGN((start & ~PAGE_MASK) + fbdev->fb_len);
> -
> -	off = vma->vm_pgoff << PAGE_SHIFT;
> -
> -	if ((vma->vm_end - vma->vm_start + off) > len) {
> -		return -EINVAL;
> -	}
> -
> -	off += start;
> -	vma->vm_pgoff = off >> PAGE_SHIFT;
> -
>  	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
>  	pgprot_val(vma->vm_page_prot) |= _CACHE_MASK; /* CCA=7 */
>  
>  	vma->vm_flags |= VM_IO;
>  
> -	return io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
> -				  vma->vm_end - vma->vm_start,
> -				  vma->vm_page_prot);
> +	return vm_iomap_memory(vma, fbdev->fb_phys, fbdev->fb_len);
>  
>  	return 0;
>  }
> -- 
> 1.8.0.2
> --
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Thank you for this backport, I'm using for the 3.5 kernel as well.

Cheers,
--
Luis
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