Re: [PATCH] mm: mremap: validate input before taking lock

[Rasmus Villemoes]

Ping...

Rasmus Villemoes <li...@rasmusvillemoes.dk> writes:

> This patch is very similar to 84d96d897671: Perform some basic
> validation of the input to mremap() before taking the
> &current->mm->mmap_sem lock. This also makes the MREMAP_FIXED =>
> MREMAP_MAYMOVE dependency slightly more explicit.
>
> Signed-off-by: Rasmus Villemoes <li...@rasmusvillemoes.dk>
> ---
>  mm/mremap.c |   18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/mm/mremap.c b/mm/mremap.c
> index 463a257..00b6905 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -456,13 +456,14 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned 
> long, old_len,
>       unsigned long charged = 0;
>       bool locked = false;
>  
> -     down_write(&current->mm->mmap_sem);
> -
>       if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
> -             goto out;
> +             return ret;
> +
> +     if (flags & MREMAP_FIXED && !(flags & MREMAP_MAYMOVE))
> +             return ret;
>  
>       if (addr & ~PAGE_MASK)
> -             goto out;
> +             return ret;
>  
>       old_len = PAGE_ALIGN(old_len);
>       new_len = PAGE_ALIGN(new_len);
> @@ -473,12 +474,13 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned 
> long, old_len,
>        * a zero new-len is nonsensical.
>        */
>       if (!new_len)
> -             goto out;
> +             return ret;
> +
> +     down_write(&current->mm->mmap_sem);
>  
>       if (flags & MREMAP_FIXED) {
> -             if (flags & MREMAP_MAYMOVE)
> -                     ret = mremap_to(addr, old_len, new_addr, new_len,
> -                                     &locked);
> +             ret = mremap_to(addr, old_len, new_addr, new_len,
> +                             &locked);
>               goto out;
>       }
>  
> -- 
> 1.7.9.5
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majord...@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"d...@kvack.org";> em...@kvack.org </a>
>

-- 
Rasmus Villemoes
<http://rasmusvillemoes.dk/>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/