From: Markus Armbruster Date: Tue, 15 Mar 2016 18:34:16 +0000 (+0100) Subject: target-ppc: Document TOCTTOU in hugepage support X-Git-Url: https://repo.jachan.dev/qemu.git/commitdiff_plain/3be5cc23245637577210e43e68dd3babd01fbb5e?hp=6741d38ad0f2405a6e999ebc9550801b01aca479 target-ppc: Document TOCTTOU in hugepage support The code to find the minimum page size is is vulnerable to TOCTTOU. Added in commit 2d103aa "target-ppc: fix hugepage support when using memory-backend-file" (v2.4.0). Since I can't fix it myself right now, add a FIXME comment. Cc: Paolo Bonzini Cc: Michael Roth Signed-off-by: Markus Armbruster Message-Id: <1458066895-20632-2-git-send-email-armbru@redhat.com> Reviewed-by: Marc-André Lureau --- diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c index 776336b8b4..2fc993143e 100644 --- a/target-ppc/kvm.c +++ b/target-ppc/kvm.c @@ -333,6 +333,12 @@ static long gethugepagesize(const char *mem_path) return fs.f_bsize; } +/* + * FIXME TOCTTOU: this iterates over memory backends' mem-path, which + * may or may not name the same files / on the same filesystem now as + * when we actually open and map them. Iterate over the file + * descriptors instead, and use qemu_fd_getpagesize(). + */ static int find_max_supported_pagesize(Object *obj, void *opaque) { char *mem_path;