On Thu, Jul 24, 2014 at 9:46 AM, Cyrill Gorcunov <gorcunov@xxxxxxxxxx> wrote:
> To eliminate code duplication lets introduce may_adjust_brk
> helper which we will use in brk() and prctl() syscalls.
>
> Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Andrew Vagin <avagin@xxxxxxxxxx>
> Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> Cc: H. Peter Anvin <hpa@xxxxxxxxx>
> Cc: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
> Cc: Vasiliy Kulikov <segoon@xxxxxxxxxxxx>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
> Cc: Julien Tinnes <jln@xxxxxxxxxx>
> ---
> include/linux/mm.h | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> Index: linux-2.6.git/include/linux/mm.h
> ===================================================================
> --- linux-2.6.git.orig/include/linux/mm.h
> +++ linux-2.6.git/include/linux/mm.h
> @@ -18,6 +18,7 @@
> #include <linux/pfn.h>
> #include <linux/bit_spinlock.h>
> #include <linux/shrinker.h>
> +#include <linux/resource.h>
>
> struct mempolicy;
> struct anon_vma;
> @@ -1780,6 +1781,19 @@ extern struct vm_area_struct *copy_vma(s
> bool *need_rmap_locks);
> extern void exit_mmap(struct mm_struct *);
>
> +static inline int may_adjust_brk(unsigned long rlim,
> + unsigned long new_brk,
> + unsigned long start_brk,
> + unsigned long end_data,
> + unsigned long start_data)
> +{
> + if (rlim < RLIMIT_DATA) {
Won't rlim always be the value from a call to rlimit(RLIMIT_DATA)? Is
there a good reason to not just put the rlimit() call in
may_adjust_brk()? This would actually be an optimization in the
prctl_set_mm case, since now it calls rlimit() unconditionally, but
doesn't need to.
-Kees
> + if (((new_brk - start_brk) + (end_data - start_data)) > rlim)
> + return -ENOSPC;
> + }
> + return 0;
> +}
> +
> extern int mm_take_all_locks(struct mm_struct *mm);
> extern void mm_drop_all_locks(struct mm_struct *mm);
>
>
--
Kees Cook
Chrome OS Security
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