* [PATCH v2] mm: Fix overflow check in expand_upwards()
@ 2017-07-02 19:24 Helge Deller
0 siblings, 0 replies; only message in thread
From: Helge Deller @ 2017-07-02 19:24 UTC (permalink / raw)
To: Hugh Dickins, linux-kernel; +Cc: Jörn Engel, linux-parisc
Jörn Engel noticed that the expand_upwards() function might not return -ENOMEM
in case the requested address is (unsigned long)-PAGE_SIZE and if the
architecture didn't defined TASK_SIZE as multiple of PAGE_SIZE.
Affected architectures are arm, frv, m68k, blackfin, h8300 and xtensa which all
define TASK_SIZE as 0xffffffff, but since none of those have an upwards-growing
stack we currently have no actual issue.
Nevertheless let's fix this just in case any of the architectures with an
upward-growing stack (currently parisc, metag and partly ia64) define TASK_SIZE
similar.
Reported-by: Jörn Engel <joern@purestorage.com>
Fixes: bd726c90b6b8 ("Allow stack to grow up to address space limit")
Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller <deller@gmx.de>
diff --git a/mm/mmap.c b/mm/mmap.c
index a5e3dcd..cc2fc8a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2232,7 +2232,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
/* Guard against exceeding limits of the address space. */
address &= PAGE_MASK;
- if (address >= TASK_SIZE)
+ if (address >= (TASK_SIZE & PAGE_MASK))
return -ENOMEM;
address += PAGE_SIZE;
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2017-07-02 19:24 [PATCH v2] mm: Fix overflow check in expand_upwards() Helge Deller
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