Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4B1FD33B6F4; Mon, 17 Aug 2026 14:31:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786977092; cv=none; b=u1/DMWYDnx/Zmd9YZB8oh0rpnSWNRknenz786nE1hjnqp5d07uhUejCUagkfzr2YR7De+AA2ICiGTRYH0j8IcbTUY7/6PPjHjAm3UnZ1BWnsS9e5ngGC6UsXZbAIUIa+dszsi4xdvAilYSzwBJ7eFcpksmQLh/huT8dufOqDW9E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786977092; c=relaxed/simple; bh=Xnfnq+qXxfG1/13INKbFHJRW3NZKnLPKybX0Zw4DBNw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EwI+l1o1mc14Z/dpvcWFbnegX/rH1/LNgmB4WFRpQr1g5tprgJTl6Gu2AgvxBqQPZ2I1K4/9cAPDEdQT/fqFn5AbQ0Ml/7IBpivYOrI8h/3bqsR9x809kG5FYMd9ucXkpFpcPTmoF1CYyeFxdjXcmVFLse+OXL+Cjuc5mn7wnQQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=T1vDnP2P; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="T1vDnP2P" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A512B1F000E9; Mon, 17 Aug 2026 14:31:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786977091; bh=90zkuutq1ZoxXSaPH89r1v5ZyHuaWEufFlT92uCmb/8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=T1vDnP2P0vgDTpLwLiQHQ1maMvquKx8E/oXJ2KVRtuFB+DmGaSDPuV4VE5x14hi45 zRVdGNYoYhoB8WHGSXM2YkaPDgJZS7qqs5D/RKneKCXxKPIS/hVtRKCPJabD8qMpWX Hd0Zo9JCyFrAU+GvVEjLxo+JFQvU5sdqRi7YFWmo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jori Koolstra , "Christian Brauner (Amutable)" Subject: [PATCH 5.15 209/456] binfmt_elf_fdpic: only honour the first PT_INTERP Date: Mon, 17 Aug 2026 15:29:59 +0200 Message-ID: <20260817132548.333869681@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132539.792407575@linuxfoundation.org> References: <20260817132539.792407575@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christian Brauner commit 3349ef6a366a61d631f6a263d12cea240957719d upstream. The program header scan handles PT_INTERP from a switch nested in the scan loop, so its break leaves the switch and not the loop. A binary carrying more than one PT_INTERP runs the case again and overwrites both interpreter_name and interpreter. The previous name allocation leaks and so does the previous interpreter reference, along with the write denial open_exec() took on it. The denial is never released, so the file stays unwritable for as long as the system runs. An unprivileged caller reaches this with a crafted binary and repeats it at will. binfmt_elf stops at the first PT_INTERP. Do the same here. The flaw dates back to the driver's introduction in the pre-git history tree introduced in v2.6.11 by 91808d6ebe39 ("[PATCH] FRV: Add FDPIC ELF binary format driver"). Link: https://patch.msgid.link/20260721-gezittert-medium-kreide-b41fc1f0277e@brauner Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reviewed-by: Jori Koolstra Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Greg Kroah-Hartman --- fs/binfmt_elf_fdpic.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -231,6 +231,10 @@ static int load_elf_fdpic_binary(struct for (i = 0; i < exec_params.hdr.e_phnum; i++, phdr++) { switch (phdr->p_type) { case PT_INTERP: + /* elf ABI allows only one interpreter */ + if (interpreter_name) + continue; + retval = -ENOMEM; if (phdr->p_filesz > PATH_MAX) goto error;