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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2019-01-29 10:48:09 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2019-02-07 11:57:01 +0100
commita0308c1315e72b6fdce7b419c4546dad568b3a83 (patch)
treea0394e6ad255922ab96a2895d9e759b530b992fd /arch/s390/mm
parentd4192437d75ae4f401aac5d54229756829015e1d (diff)
downloadlinux-a0308c1315e72b6fdce7b419c4546dad568b3a83.tar.bz2
s390/mmap: take stack_guard_gap into account for mmap_base
The s390 version of the mmap_base function is ignorant of stack_guard_gap which can lead to a placement of the stack vs. the mmap base that does not leave enough space for the stack rlimit. Add the stack_guard_gap to the calculation and while we are at it the check for gap+pad overflows as well. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/mm')
-rw-r--r--arch/s390/mm/mmap.c33
1 files changed, 19 insertions, 14 deletions
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 0a7627cdb34e..687f2a4d3459 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -29,14 +29,6 @@ static unsigned long stack_maxrandom_size(void)
return STACK_RND_MASK << PAGE_SHIFT;
}
-/*
- * Top of mmap area (just below the process stack).
- *
- * Leave at least a ~32 MB hole.
- */
-#define MIN_GAP (32*1024*1024)
-#define MAX_GAP (STACK_TOP/6*5)
-
static inline int mmap_is_legacy(struct rlimit *rlim_stack)
{
if (current->personality & ADDR_COMPAT_LAYOUT)
@@ -60,13 +52,26 @@ static inline unsigned long mmap_base(unsigned long rnd,
struct rlimit *rlim_stack)
{
unsigned long gap = rlim_stack->rlim_cur;
+ unsigned long pad = stack_maxrandom_size() + stack_guard_gap;
+ unsigned long gap_min, gap_max;
+
+ /* Values close to RLIM_INFINITY can overflow. */
+ if (gap + pad > gap)
+ gap += pad;
+
+ /*
+ * Top of mmap area (just below the process stack).
+ * Leave at least a ~32 MB hole.
+ */
+ gap_min = 32 * 1024 * 1024UL;
+ gap_max = (STACK_TOP / 6) * 5;
+
+ if (gap < gap_min)
+ gap = gap_min;
+ else if (gap > gap_max)
+ gap = gap_max;
- if (gap < MIN_GAP)
- gap = MIN_GAP;
- else if (gap > MAX_GAP)
- gap = MAX_GAP;
- gap &= PAGE_MASK;
- return STACK_TOP - stack_maxrandom_size() - rnd - gap;
+ return PAGE_ALIGN(STACK_TOP - gap - rnd);
}
unsigned long