From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45998) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fV5iB-0001mp-Hc for qemu-devel@nongnu.org; Mon, 18 Jun 2018 21:45:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fV5i8-0008SU-Fb for qemu-devel@nongnu.org; Mon, 18 Jun 2018 21:45:35 -0400 Sender: fluxion From: Michael Roth Date: Mon, 18 Jun 2018 20:42:06 -0500 Message-Id: <20180619014319.28272-41-mdroth@linux.vnet.ibm.com> In-Reply-To: <20180619014319.28272-1-mdroth@linux.vnet.ibm.com> References: <20180619014319.28272-1-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 040/113] multiboot: Reject kernels exceeding the address space List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Kevin Wolf From: Kevin Wolf The code path where mh_load_end_addr is non-zero in the Multiboot header checks that mh_load_end_addr >= mh_load_addr and so mb_load_size is checked. However, mb_load_size is not checked when calculated from the file size, when mh_load_end_addr is 0. If the kernel binary size is larger than can fit in the address space after load_addr, we ended up with a kernel_size that is smaller than load_size, which means that we read the file into a too small buffer. Add a check to reject kernel files with such Multiboot headers. Signed-off-by: Kevin Wolf Reviewed-by: Jack Schwartz (cherry picked from commit b17a9054a0652a1481be48a6729e972abf02412f) Signed-off-by: Michael Roth --- hw/i386/multiboot.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/i386/multiboot.c b/hw/i386/multiboot.c index d9a0a95a2f..775aa5bfd0 100644 --- a/hw/i386/multiboot.c +++ b/hw/i386/multiboot.c @@ -247,6 +247,10 @@ int load_multiboot(FWCfgState *fw_cfg, } mb_load_size = kernel_file_size - mb_kernel_text_offset; } + if (mb_load_size > UINT32_MAX - mh_load_addr) { + error_report("kernel does not fit in address space"); + exit(1); + } if (mh_bss_end_addr) { if (mh_bss_end_addr < (mh_load_addr + mb_load_size)) { error_report("invalid bss_end_addr address"); -- 2.11.0