Re: [Xen-devel] [PATCH for-4.10] string: fix memmove when size is 0

2017-10-20 Thread Roger Pau Monné
On Fri, Oct 20, 2017 at 01:17:40AM -0600, Jan Beulich wrote: > >>> On 17.10.17 at 14:03, wrote: > > --- a/xen/arch/x86/string.c > > +++ b/xen/arch/x86/string.c > > @@ -39,6 +39,9 @@ void *(memmove)(void *dest, const void *src, size_t n) > > { > > long d0, d1, d2; > > > > +if ( !n ) > >

Re: [Xen-devel] [PATCH for-4.10] string: fix memmove when size is 0

2017-10-20 Thread Jan Beulich
>>> On 17.10.17 at 14:03, wrote: > --- a/xen/arch/x86/string.c > +++ b/xen/arch/x86/string.c > @@ -39,6 +39,9 @@ void *(memmove)(void *dest, const void *src, size_t n) > { > long d0, d1, d2; > > +if ( !n ) > +return; Actually - I can't see how this would build successfully: Th

Re: [Xen-devel] [PATCH for-4.10] string: fix memmove when size is 0

2017-10-18 Thread Jan Beulich
>>> On 18.10.17 at 12:44, wrote: > On Tue, Oct 17, 2017 at 07:00:25AM -0600, Jan Beulich wrote: >> >>> On 17.10.17 at 14:52, wrote: >> > On Tue, Oct 17, 2017 at 01:41:35PM +0100, Andrew Cooper wrote: >> >> There are many passed values which could trigger this warning. Does >> >> >> >> diff --gi

Re: [Xen-devel] [PATCH for-4.10] string: fix memmove when size is 0

2017-10-18 Thread Julien Grall
Hi Roger, On 10/18/2017 11:44 AM, Roger Pau Monné wrote: On Tue, Oct 17, 2017 at 07:00:25AM -0600, Jan Beulich wrote: On 17.10.17 at 14:52, wrote: On Tue, Oct 17, 2017 at 01:41:35PM +0100, Andrew Cooper wrote: There are many passed values which could trigger this warning. Does diff --git a

Re: [Xen-devel] [PATCH for-4.10] string: fix memmove when size is 0

2017-10-18 Thread Roger Pau Monné
On Tue, Oct 17, 2017 at 07:00:25AM -0600, Jan Beulich wrote: > >>> On 17.10.17 at 14:52, wrote: > > On Tue, Oct 17, 2017 at 01:41:35PM +0100, Andrew Cooper wrote: > >> There are many passed values which could trigger this warning. Does > >> > >> diff --git a/xen/arch/x86/string.c b/xen/arch/x86/

Re: [Xen-devel] [PATCH for-4.10] string: fix memmove when size is 0

2017-10-17 Thread Jan Beulich
>>> On 17.10.17 at 14:52, wrote: > On Tue, Oct 17, 2017 at 01:41:35PM +0100, Andrew Cooper wrote: >> There are many passed values which could trigger this warning. Does >> >> diff --git a/xen/arch/x86/string.c b/xen/arch/x86/string.c >> index cd85a38..4f55856 100644 >> --- a/xen/arch/x86/string.

Re: [Xen-devel] [PATCH for-4.10] string: fix memmove when size is 0

2017-10-17 Thread Roger Pau Monné
On Tue, Oct 17, 2017 at 01:41:35PM +0100, Andrew Cooper wrote: > On 17/10/17 13:03, Roger Pau Monne wrote: > > ubsan in clang 5.0 complains with: > > > > (XEN) UBSAN: Undefined behaviour in string.c:50:28 > > (XEN) pointer overflow: > > (XEN) addition of unsigned offset to 8310 overflow

Re: [Xen-devel] [PATCH for-4.10] string: fix memmove when size is 0

2017-10-17 Thread Andrew Cooper
On 17/10/17 13:03, Roger Pau Monne wrote: > ubsan in clang 5.0 complains with: > > (XEN) UBSAN: Undefined behaviour in string.c:50:28 > (XEN) pointer overflow: > (XEN) addition of unsigned offset to 8310 overflowed to > 830f > [...] > (XEN) Xen call trace: > (XEN)[] ubs

Re: [Xen-devel] [PATCH for-4.10] string: fix memmove when size is 0

2017-10-17 Thread Jan Beulich
>>> On 17.10.17 at 14:03, wrote: > --- a/xen/arch/x86/string.c > +++ b/xen/arch/x86/string.c > @@ -39,6 +39,9 @@ void *(memmove)(void *dest, const void *src, size_t n) > { > long d0, d1, d2; > > +if ( !n ) > +return; memmove() hopefully isn't on any really hot path, so the ext

[Xen-devel] [PATCH for-4.10] string: fix memmove when size is 0

2017-10-17 Thread Roger Pau Monne
ubsan in clang 5.0 complains with: (XEN) UBSAN: Undefined behaviour in string.c:50:28 (XEN) pointer overflow: (XEN) addition of unsigned offset to 8310 overflowed to 830f [...] (XEN) Xen call trace: (XEN)[] ubsan.c#ubsan_epilogue+0xd/0xc0 (XEN)[] __ubsan_handle_poi