From: Helge Deller <deller@xxxxxx> Subject: 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. Link: http://lkml.kernel.org/r/20170702192452.GA11868@xxxxxxxx Fixes: bd726c90b6b8 ("Allow stack to grow up to address space limit") Signed-off-by: Helge Deller <deller@xxxxxx> Reported-by: Jörn Engel <joern@xxxxxxxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/mmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN mm/mmap.c~mm-fix-overflow-check-in-expand_upwards mm/mmap.c --- a/mm/mmap.c~mm-fix-overflow-check-in-expand_upwards +++ a/mm/mmap.c @@ -2231,7 +2231,7 @@ 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; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
