Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932354AbbKXWgp (ORCPT ); Tue, 24 Nov 2015 17:36:45 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:40316 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755453AbbKXWfl (ORCPT ); Tue, 24 Nov 2015 17:35:41 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Al Viro" , "Maciej W. Rozycki" Date: Tue, 24 Nov 2015 22:33:59 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 45/52] binfmt_elf: Don't clobber passed executable's file header In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.247 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2580 Lines: 66 3.2.74-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: "Maciej W. Rozycki" commit b582ef5c53040c5feef4c96a8f9585b6831e2441 upstream. Do not clobber the buffer space passed from `search_binary_handler' and originally preloaded by `prepare_binprm' with the executable's file header by overwriting it with its interpreter's file header. Instead keep the buffer space intact and directly use the data structure locally allocated for the interpreter's file header, fixing a bug introduced in 2.1.14 with loadable module support (linux-mips.org commit beb11695 [Import of Linux/MIPS 2.1.14], predating kernel.org repo's history). Adjust the amount of data read from the interpreter's file accordingly. This was not an issue before loadable module support, because back then `load_elf_binary' was executed only once for a given ELF executable, whether the function succeeded or failed. With loadable module support supported and enabled, upon a failure of `load_elf_binary' -- which may for example be caused by architecture code rejecting an executable due to a missing hardware feature requested in the file header -- a module load is attempted and then the function reexecuted by `search_binary_handler'. With the executable's file header replaced with its interpreter's file header the executable can then be erroneously accepted in this subsequent attempt. Signed-off-by: Maciej W. Rozycki Signed-off-by: Al Viro Signed-off-by: Ben Hutchings --- fs/binfmt_elf.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -671,16 +671,16 @@ static int load_elf_binary(struct linux_ */ would_dump(bprm, interpreter); - retval = kernel_read(interpreter, 0, bprm->buf, - BINPRM_BUF_SIZE); - if (retval != BINPRM_BUF_SIZE) { + /* Get the exec headers */ + retval = kernel_read(interpreter, 0, + (void *)&loc->interp_elf_ex, + sizeof(loc->interp_elf_ex)); + if (retval != sizeof(loc->interp_elf_ex)) { if (retval >= 0) retval = -EIO; goto out_free_dentry; } - /* Get the exec headers */ - loc->interp_elf_ex = *((struct elfhdr *)bprm->buf); break; } elf_ppnt++; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/