On Thu, Jan 26, 2017 at 11:22:54AM +0100, Ingo Molnar wrote: > 'size_total' is derived from an unsigned input parameter - and then converted > to 'int' and checked for negative ranges: > > if (size_total < 0 || offset < size_total) { > > This conversion and the checks are unnecessary obfuscation, reject overly > large requested copy sizes outright and simplify the underlying code. > > Reported-by: Rik van Riel <r...@redhat.com> > Cc: Andy Lutomirski <l...@kernel.org> > Cc: Borislav Petkov <b...@alien8.de> > Cc: Dave Hansen <dave.han...@linux.intel.com> > Cc: Fenghua Yu <fenghua...@intel.com> > Cc: H. Peter Anvin <h...@zytor.com> > Cc: Linus Torvalds <torva...@linux-foundation.org> > Cc: Oleg Nesterov <o...@redhat.com> > Cc: Thomas Gleixner <t...@linutronix.de> > Cc: Yu-cheng Yu <yu-cheng...@intel.com> > Cc: Fenghua Yu <fenghua...@intel.com> > Signed-off-by: Ingo Molnar <mi...@kernel.org> > --- > arch/x86/kernel/fpu/xstate.c | 32 +++++++++++++++----------------- > 1 file changed, 15 insertions(+), 17 deletions(-) > > diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c > index 8f9da89015e6..cceabca485c8 100644 > --- a/arch/x86/kernel/fpu/xstate.c > +++ b/arch/x86/kernel/fpu/xstate.c > @@ -924,15 +924,11 @@ int arch_set_user_pkey_access(struct task_struct *tsk, > int pkey, > * the source data pointer or increment pos, count, kbuf, and ubuf. > */ > static inline int > -__copy_xstate_to_kernel(void *kbuf, > - const void *data, > - unsigned int offset, unsigned int size, int size_total) > +__copy_xstate_to_kernel(void *kbuf, const void *data, > + unsigned int offset, unsigned int size, unsigned int > size_total) > { > - if (!size) > - return 0; > - > - if (size_total < 0 || offset < size_total) { > - unsigned int copy = size_total < 0 ? size : min(size, > size_total - offset); > + if (offset < size_total) { > + unsigned int copy = min(size, size_total - offset); > > memcpy(kbuf + offset, data, copy); > } > @@ -985,12 +981,13 @@ int copy_xstate_to_kernel(void *kbuf, struct > xregs_state *xsave, unsigned int of > offset = xstate_offsets[i]; > size = xstate_sizes[i]; > > + /* The next component has to fit fully into the output > buffer: */ > + if (offset + size > size_total) > + break;
This makes sense, but would be different from the non-compacted format path where this rule is not enforced. Do we want to unify both? Yu-cheng