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mm: fix overflow check in expand_upwards()

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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.

Link: http://lkml.kernel.org/r/[email protected]
Fixes: bd726c90b6 ("Allow stack to grow up to address space limit")
Signed-off-by: Helge Deller <[email protected]>
Reported-by: Jörn Engel <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Helge Deller 2017-07-14 14:49:38 -07:00 • committed by Linus Torvalds
commit 37511fb5c9
1 changed files with 1 additions and 1 deletions
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2
mm/mmap.c
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@ -2231,7 +2231,7 @@ 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;