Messages in this thread | | | Date | Thu, 4 Sep 2014 13:14:08 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] kern/sys: Compat sysinfo syscall fix undefined behavior |
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On Thu, 04 Sep 2014 12:46:53 -0600 Scotty Bauer <sbauer@eng.utah.edu> wrote:
> Fix undefined behavior and compiler warning by replacing right > shift 32 with upper_32_bits macro > > Signed-off-by: Scotty Bauer <sbauer@eng.utah.edu> > --- > kernel/sys.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sys.c b/kernel/sys.c > index ce81291..c78530b 100644 > --- a/kernel/sys.c > +++ b/kernel/sys.c > @@ -2135,7 +2135,7 @@ COMPAT_SYSCALL_DEFINE1(sysinfo, struct compat_sysinfo __user *, info) > /* Check to see if any memory value is too large for 32-bit and scale > * down if needed > */ > - if ((s.totalram >> 32) || (s.totalswap >> 32)) { > + if (upper_32_bits(s.totalram) || upper_32_bits(s.totalswap)) { > int bitcount = 0; > > while (s.mem_unit < PAGE_SIZE) {
Fair enough.
If I'm reading it correctly, this is all dead code because si_meminfo() unconditionally sets sysinfo.mem_unit to PAGE_SIZE.
It could all do with a bit of a cleanup, I suspect.
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