| From | Ben Hutchings <> | Date | Mon, 09 Oct 2017 13:30:34 +0100 | Subject | [PATCH 3.2 46/74] mm: fix overflow check in expand_upwards() |
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3.2.94-rc1 review patch. If anyone has any objections, please let me know.
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From: Helge Deller <deller@gmx.de>
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.
Link: http://lkml.kernel.org/r/20170702192452.GA11868@p100.box Fixes: bd726c90b6b8 ("Allow stack to grow up to address space limit") Signed-off-by: Helge Deller <deller@gmx.de> Reported-by: Jörn Engel <joern@purestorage.com> Cc: Hugh Dickins <hughd@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- mm/mmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/mmap.c +++ b/mm/mmap.c @@ -1717,7 +1717,7 @@ 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;
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