On Mon, Oct 05, 2020 at 05:11:19PM +0300, Jarkko Sakkinen wrote: > Fix the issue further discussed in: No, this is still utter crap. Just use the version I sent. > 1. https://lore.kernel.org/linux-sgx/op.0rwbv916wjvjmi@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > 2. https://lore.kernel.org/linux-sgx/20201003195440.GD20115@xxxxxxxxxxxxxxxxxxxx/ > > Reported-by: Haitao Huang <haitao.huang@xxxxxxxxxxxxxxx> > Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx> > Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> > Cc: Jethro Beekman <jethro@xxxxxxxxxxxx> > Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> > --- > v3: > * Added the missing unlock pointed out by Matthew. > * Tested with the correct patch (last time had v1 applied) > * I don't know what happened to v2 changelog, checked from patchwork > and it wasn't there. Hope this is not scraped. > arch/x86/kernel/cpu/sgx/encl.c | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c > index 4c6407cd857a..e91e521b03a8 100644 > --- a/arch/x86/kernel/cpu/sgx/encl.c > +++ b/arch/x86/kernel/cpu/sgx/encl.c > @@ -307,6 +307,8 @@ int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start, > unsigned long idx_start = PFN_DOWN(start); > unsigned long idx_end = PFN_DOWN(end - 1); > struct sgx_encl_page *page; > + unsigned long count = 0; > + int ret = 0; > > XA_STATE(xas, &encl->page_array, idx_start); > > @@ -317,11 +319,30 @@ int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start, > if (current->personality & READ_IMPLIES_EXEC) > return -EACCES; > > - xas_for_each(&xas, page, idx_end) > - if (!page || (~page->vm_max_prot_bits & vm_prot_bits)) > - return -EACCES; > + /* > + * No need to hold encl->lock: > + * 1. None of the page->* get written. > + * 2. page->vm_max_prot_bits is set in sgx_encl_page_alloc(). This > + * is before calling xa_insert(). After that it is never modified. > + */ > + xas_lock(&xas); > + xas_for_each(&xas, page, idx_end) { > + if (++count % XA_CHECK_SCHED) > + continue; > > - return 0; > + if (!page || (~page->vm_max_prot_bits & vm_prot_bits)) { > + ret = -EACCES; > + break; > + } > + > + xas_pause(&xas); > + xas_unlock(&xas); > + cond_resched(); > + xas_lock(&xas); > + } > + xas_unlock(&xas); > + > + return ret; > } > > static int sgx_vma_mprotect(struct vm_area_struct *vma, > -- > 2.25.1 >
