From: Boris Ostrovsky Date: Wed, 6 Jan 2016 20:03:21 +0000 (-0500) Subject: libxc: Don't write terminating NULL character to command string X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~2008 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=8345512febd09e39c55bdf76ee0fb41b32562f45;p=xen.git libxc: Don't write terminating NULL character to command string When copying boot command string for HVMlite guests we explicitly write '\0' at MAX_GUEST_CMDLINE offset. Unless the string is close to MAX_GUEST_CMDLINE in length this write will end up in the wrong place, beyond the end of the mapped range. We don't need to limit the size of command string to some arbitrary number. Any size that can be successfully allocated and mapped is valid and so the string is guaranteed to be NULL-terminated (since we use strlen, which needs terminating '\0', to calculate allocation size). Signed-off-by: Boris Ostrovsky Acked-by: Wei Liu --- diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c index 39608752d0..b8d290464b 100644 --- a/tools/libxc/xc_dom_x86.c +++ b/tools/libxc/xc_dom_x86.c @@ -676,8 +676,7 @@ static int alloc_magic_pages_hvm(struct xc_dom_image *dom) if ( dom->cmdline ) { - strncpy(cmdline, dom->cmdline, MAX_GUEST_CMDLINE); - cmdline[MAX_GUEST_CMDLINE - 1] = '\0'; + strncpy(cmdline, dom->cmdline, cmdline_size); start_info->cmdline_paddr = (seg.pfn << PAGE_SHIFT) + ((uintptr_t)cmdline - (uintptr_t)start_info); }