[rfc 2/4] mm: Use may_adjust_brk helper

[Cyrill Gorcunov]

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>
---
 kernel/sys.c |   10 ++++------
 mm/mmap.c    |    7 +++----
 2 files changed, 7 insertions(+), 10 deletions(-)

Index: linux-2.6.git/kernel/sys.c
===================================================================
--- linux-2.6.git.orig/kernel/sys.c
+++ linux-2.6.git/kernel/sys.c
@@ -1733,9 +1733,8 @@ static int prctl_set_mm(int opt, unsigne
 		if (addr <= mm->end_data)
 			goto out;
 
-		if (rlim < RLIM_INFINITY &&
-		    (mm->brk - addr) +
-		    (mm->end_data - mm->start_data) > rlim)
+		if (may_adjust_brk(rlim, mm->brk, addr,
+				   mm->end_data, mm->start_data))
 			goto out;
 
 		mm->start_brk = addr;
@@ -1745,9 +1744,8 @@ static int prctl_set_mm(int opt, unsigne
 		if (addr <= mm->end_data)
 			goto out;
 
-		if (rlim < RLIM_INFINITY &&
-		    (addr - mm->start_brk) +
-		    (mm->end_data - mm->start_data) > rlim)
+		if (may_adjust_brk(rlim, addr, mm->start_brk,
+				   mm->end_data, mm->start_data))
 			goto out;
 
 		mm->brk = addr;
Index: linux-2.6.git/mm/mmap.c
===================================================================
--- linux-2.6.git.orig/mm/mmap.c
+++ linux-2.6.git/mm/mmap.c
@@ -263,7 +263,7 @@ static unsigned long do_brk(unsigned lon
 
 SYSCALL_DEFINE1(brk, unsigned long, brk)
 {
-	unsigned long rlim, retval;
+	unsigned long retval;
 	unsigned long newbrk, oldbrk;
 	struct mm_struct *mm = current->mm;
 	unsigned long min_brk;
@@ -293,9 +293,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 	 * segment grow beyond its set limit the in case where the limit is
 	 * not page aligned -Ram Gupta
 	 */
-	rlim = rlimit(RLIMIT_DATA);
-	if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
-			(mm->end_data - mm->start_data) > rlim)
+	if (may_adjust_brk(rlimit(RLIMIT_DATA), brk, mm->start_brk,
+			   mm->end_data, mm->start_data))
 		goto out;
 
 	newbrk = PAGE_ALIGN(brk);

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