From 6877a6c456178d6c1ca9a0ffaabaa7e51105b2ac Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Mon, 27 Jan 2020 19:01:22 +0100 Subject: [PATCH 051/116] virtiofsd: validate input buffer sizes in do_write_buf() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Dr. David Alan Gilbert Message-id: <20200127190227.40942-48-dgilbert@redhat.com> Patchwork-id: 93501 O-Subject: [RHEL-AV-8.2 qemu-kvm PATCH 047/112] virtiofsd: validate input buffer sizes in do_write_buf() Bugzilla: 1694164 RH-Acked-by: Philippe Mathieu-Daudé RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Sergio Lopez Pascual From: Stefan Hajnoczi There is a small change in behavior: if fuse_write_in->size doesn't match the input buffer size then the request is failed. Previously write requests with 1 fuse_buf element would truncate to fuse_write_in->size. Signed-off-by: Stefan Hajnoczi Reviewed-by: Sergio Lopez Signed-off-by: Dr. David Alan Gilbert (cherry picked from commit 0ba8c3c6fce8fe949d59c1fd84d98d220ef9e759) Signed-off-by: Miroslav Rezanina --- tools/virtiofsd/fuse_lowlevel.c | 49 +++++++++++++++++++++++++---------------- 1 file changed, 30 insertions(+), 19 deletions(-) diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c index 7e10995..611e8b0 100644 --- a/tools/virtiofsd/fuse_lowlevel.c +++ b/tools/virtiofsd/fuse_lowlevel.c @@ -1003,8 +1003,8 @@ static void do_write(fuse_req_t req, fuse_ino_t nodeid, const void *inarg) } } -static void do_write_buf(fuse_req_t req, fuse_ino_t nodeid, const void *inarg, - struct fuse_bufvec *ibufv) +static void do_write_buf(fuse_req_t req, fuse_ino_t nodeid, + struct fuse_mbuf_iter *iter, struct fuse_bufvec *ibufv) { struct fuse_session *se = req->se; struct fuse_bufvec *pbufv = ibufv; @@ -1012,28 +1012,27 @@ static void do_write_buf(fuse_req_t req, fuse_ino_t nodeid, const void *inarg, .buf[0] = ibufv->buf[0], .count = 1, }; - struct fuse_write_in *arg = (struct fuse_write_in *)inarg; + struct fuse_write_in *arg; + size_t arg_size = sizeof(*arg); struct fuse_file_info fi; memset(&fi, 0, sizeof(fi)); + + arg = fuse_mbuf_iter_advance(iter, arg_size); + if (!arg) { + fuse_reply_err(req, EINVAL); + return; + } + + fi.lock_owner = arg->lock_owner; + fi.flags = arg->flags; fi.fh = arg->fh; fi.writepage = arg->write_flags & FUSE_WRITE_CACHE; if (ibufv->count == 1) { - fi.lock_owner = arg->lock_owner; - fi.flags = arg->flags; - if (!(tmpbufv.buf[0].flags & FUSE_BUF_IS_FD)) { - tmpbufv.buf[0].mem = PARAM(arg); - } - tmpbufv.buf[0].size -= - sizeof(struct fuse_in_header) + sizeof(struct fuse_write_in); - if (tmpbufv.buf[0].size < arg->size) { - fuse_log(FUSE_LOG_ERR, - "fuse: do_write_buf: buffer size too small\n"); - fuse_reply_err(req, EIO); - return; - } - tmpbufv.buf[0].size = arg->size; + assert(!(tmpbufv.buf[0].flags & FUSE_BUF_IS_FD)); + tmpbufv.buf[0].mem = ((char *)arg) + arg_size; + tmpbufv.buf[0].size -= sizeof(struct fuse_in_header) + arg_size; pbufv = &tmpbufv; } else { /* @@ -1043,6 +1042,13 @@ static void do_write_buf(fuse_req_t req, fuse_ino_t nodeid, const void *inarg, ibufv->buf[0].size = 0; } + if (fuse_buf_size(pbufv) != arg->size) { + fuse_log(FUSE_LOG_ERR, + "fuse: do_write_buf: buffer size doesn't match arg->size\n"); + fuse_reply_err(req, EIO); + return; + } + se->op.write_buf(req, nodeid, pbufv, arg->offset, &fi); } @@ -2052,12 +2058,17 @@ void fuse_session_process_buf_int(struct fuse_session *se, struct fuse_chan *ch) { const struct fuse_buf *buf = bufv->buf; + struct fuse_mbuf_iter iter = FUSE_MBUF_ITER_INIT(buf); struct fuse_in_header *in; const void *inarg; struct fuse_req *req; int err; - in = buf->mem; + /* The first buffer must be a memory buffer */ + assert(!(buf->flags & FUSE_BUF_IS_FD)); + + in = fuse_mbuf_iter_advance(&iter, sizeof(*in)); + assert(in); /* caller guarantees the input buffer is large enough */ if (se->debug) { fuse_log(FUSE_LOG_DEBUG, @@ -2129,7 +2140,7 @@ void fuse_session_process_buf_int(struct fuse_session *se, inarg = (void *)&in[1]; if (in->opcode == FUSE_WRITE && se->op.write_buf) { - do_write_buf(req, in->nodeid, inarg, bufv); + do_write_buf(req, in->nodeid, &iter, bufv); } else { fuse_ll_ops[in->opcode].func(req, in->nodeid, inarg); } -- 1.8.3.1