mm: fix overflow check in expand_upwards()

commit 37511fb5c9 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.

Fixes: bd726c90b6 ("Allow stack to grow up to address space limit")
Signed-off-by: Helge Deller <>
Reported-by: Jörn Engel <>
Cc: Hugh Dickins <>
Cc: Oleg Nesterov <>
Signed-off-by: Andrew Morton <>
Signed-off-by: Linus Torvalds <>
Signed-off-by: Greg Kroah-Hartman <>
Helge Deller 2017-07-14 14:49:38 -07:00 committed by Greg Kroah-Hartman
parent 1e6f1af808
commit 38dfd2e3a6
1 changed files with 1 additions and 1 deletions

View File

@ -2228,7 +2228,7 @@ 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;