Commit 37511fb5 authored by Helge Deller's avatar Helge Deller Committed by Linus Torvalds
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mm: fix overflow check in expand_upwards()

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.

Fixes: bd726c90

 ("Allow stack to grow up to address space limit")
Signed-off-by: default avatarHelge Deller <>
Reported-by: default avatarJörn Engel <>
Cc: Hugh Dickins <>
Cc: Oleg Nesterov <>
Cc: <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent b86faee6
......@@ -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;
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