Patch "mm: fix overflow check in expand_upwards()" has been added to the 4.12-stable tree

This is a note to let you know that I've just added the patch titled

mm: fix overflow check in expand_upwards()

to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mm-fix-overflow-check-in-expand_upwards.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Helge Deller <[email protected]>
Date: Fri, 14 Jul 2017 14:49:38 -0700
Subject: mm: fix overflow check in expand_upwards()
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From: Helge Deller <[email protected]>

commit 37511fb5c91db93d8bd6e3f52f86e5a7ff7cfcdf upstream.

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.

---
 mm/mmap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -2232,7 +2232,7 @@ int expand_upwards(struct vm_area_struct
 
 	/* 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;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.12/parisc-use-compat_sys_keyctl.patch queue-4.12/mm-fix-overflow-check-in-expand_upwards.patch queue-4.12/parisc-dma-api-return-error-instead-of-bug_on-for-dma-ops-on-non-dma-devs.patch queue-4.12/parisc-mm-ensure-irqs-are-off-in-switch_mm.patch queue-4.12/parisc-report-sigsegv-instead-of-sigbus-when-running-out-of-stack.patch