On Sat, Sep 14, 2019 at 02:54:11AM +0200, Stefan Lippers-Hollmann wrote: > Hi > > On 2019-09-13, Greg Kroah-Hartman wrote: > > From: Michael S. Tsirkin <mst@xxxxxxxxxx> > > > > commit a89db445fbd7f1f8457b03759aa7343fa530ef6b upstream. > > > > iovec addresses coming from vhost are assumed to be > > pre-validated, but in fact can be speculated to a value > > out of range. > > > > Userspace address are later validated with array_index_nospec so we can > > be sure kernel info does not leak through these addresses, but vhost > > must also not leak userspace info outside the allowed memory table to > > guests. > > > > Following the defence in depth principle, make sure > > the address is not validated out of node range. > [...] > > This fails to compile as part of 5.2.15-rc1 on i386 (amd64 is fine), using > gcc 9.2.1. Reverting just this patch results in a successful build again. > > > --- a/drivers/vhost/vhost.c > > +++ b/drivers/vhost/vhost.c > > @@ -1965,8 +1965,10 @@ static int translate_desc(struct vhost_v > > _iov = iov + ret; > > size = node->size - addr + node->start; > > _iov->iov_len = min((u64)len - s, size); > > - _iov->iov_base = (void __user *)(unsigned long) > > - (node->userspace_addr + addr - node->start); > > + _iov->iov_base = (void __user *) > > + ((unsigned long)node->userspace_addr + > > + array_index_nospec((unsigned long)(addr - node->start), > > + node->size)); > > s += size; > > addr += size; > > ++ret; > > > > > > CC [M] drivers/vhost/vhost.o > In file included from /build/linux-5.2/include/linux/export.h:45, > from /build/linux-5.2/include/linux/linkage.h:7, > from /build/linux-5.2/include/linux/kernel.h:8, > from /build/linux-5.2/include/linux/list.h:9, > from /build/linux-5.2/include/linux/wait.h:7, > from /build/linux-5.2/include/linux/eventfd.h:13, > from /build/linux-5.2/drivers/vhost/vhost.c:13: > /build/linux-5.2/drivers/vhost/vhost.c: In function 'translate_desc': > /build/linux-5.2/include/linux/compiler.h:345:38: error: call to '__compiletime_assert_1970' declared with attribute error: BUILD_BUG_ON failed: sizeof(_s) > sizeof(long) > 345 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > | ^ > /build/linux-5.2/include/linux/compiler.h:326:4: note: in definition of macro '__compiletime_assert' > 326 | prefix ## suffix(); \ > | ^~~~~~ > /build/linux-5.2/include/linux/compiler.h:345:2: note: in expansion of macro '_compiletime_assert' > 345 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > | ^~~~~~~~~~~~~~~~~~~ > /build/linux-5.2/include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > | ^~~~~~~~~~~~~~~~~~ > /build/linux-5.2/include/linux/build_bug.h:50:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' > 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) > | ^~~~~~~~~~~~~~~~ > /build/linux-5.2/include/linux/nospec.h:56:2: note: in expansion of macro 'BUILD_BUG_ON' > 56 | BUILD_BUG_ON(sizeof(_s) > sizeof(long)); \ > | ^~~~~~~~~~~~ > /build/linux-5.2/drivers/vhost/vhost.c:1970:5: note: in expansion of macro 'array_index_nospec' > 1970 | array_index_nospec((unsigned long)(addr - node->start), > | ^~~~~~~~~~~~~~~~~~ > make[3]: *** [/build/linux-5.2/scripts/Makefile.build:285: drivers/vhost/vhost.o] Error 1 > make[2]: *** [/build/linux-5.2/scripts/Makefile.build:489: drivers/vhost] Error 2 > make[1]: *** [/build/linux-5.2/Makefile:1072: drivers] Error 2 > make: *** [/build/linux-5.2/Makefile:179: sub-make] Error 2 Do you have the same problem with Linus's tree right now? thanks, greg k-h
