From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7F7CE3FFE; Tue, 23 Jan 2024 00:11:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705968694; cv=none; b=Jw+WwMdN3bSG1mbHYke/uGHqtRln5JM8Nz8AZd0lOE0NBo5DQX5mNtaVJzJ4USiQlTeLWrJJjGv4AmqH9ysJrdBW2lM+o48DBbTsr52nht0AaejC+ZPIuM6AeuNfXOQqSvwhZQkCzAf2x0rhOD1b/Npwu6zdcaexH5iLx5CPXYg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705968694; c=relaxed/simple; bh=OzWqp4Hrw9krY1bDFRo6DRYHw4R0Sks9t7crT05JB9Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HdLIeHsQjpwglUjH4VJANlHB+H5UAXEF/cKrmiXuprcTv+2VivASz7GDw3NoIiTkNP1h+HelNroIyL+IZrTBGf5JXuEAbvuffRrV3EpwNv6/trNLSpZWTkFdigNqQMENdwuszmAxkVrhwdDiklxG+GgMOsO+EUlAMhEl7cDz/LU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Km03q860; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Km03q860" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B1ADC433F1; Tue, 23 Jan 2024 00:11:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1705968694; bh=OzWqp4Hrw9krY1bDFRo6DRYHw4R0Sks9t7crT05JB9Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Km03q860r7nMYQgYVnE+hcJi1S09X4sG8pUmc2WgPZmd5JE6jsOZkDVbnBd51MztT oiD1SY0hHCSqlHaJ+bg3wdGUMAZVs30K19j3uIylHyN0TDOalTR1tvMM2obF9/UHgW EetV5PGb59x25tAGlWubFvPUyBPdywUKGezW+Mfc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Wang Xiayang , Daniel Thompson , Douglas Anderson , Sasha Levin Subject: [PATCH 4.19 143/148] kdb: Censor attempts to set PROMPT without ENABLE_MEM_READ Date: Mon, 22 Jan 2024 15:58:19 -0800 Message-ID: <20240122235718.398448224@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240122235712.442097787@linuxfoundation.org> References: <20240122235712.442097787@linuxfoundation.org> User-Agent: quilt/0.67 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 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Thompson [ Upstream commit ad99b5105c0823ff02126497f4366e6a8009453e ] Currently the PROMPT variable could be abused to provoke the printf() machinery to read outside the current stack frame. Normally this doesn't matter becaues md is already a much better tool for reading from memory. However the md command can be disabled by not setting KDB_ENABLE_MEM_READ. Let's also prevent PROMPT from being modified in these circumstances. Whilst adding a comment to help future code reviewers we also remove the #ifdef where PROMPT in consumed. There is no problem passing an unused (0) to snprintf when !CONFIG_SMP. argument Reported-by: Wang Xiayang Signed-off-by: Daniel Thompson Reviewed-by: Douglas Anderson Stable-dep-of: 4f41d30cd6dc ("kdb: Fix a potential buffer overflow in kdb_local()") Signed-off-by: Sasha Levin --- kernel/debug/kdb/kdb_main.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index dc6bf35e7884..8f31d472384f 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -399,6 +399,13 @@ int kdb_set(int argc, const char **argv) if (argc != 2) return KDB_ARGCOUNT; + /* + * Censor sensitive variables + */ + if (strcmp(argv[1], "PROMPT") == 0 && + !kdb_check_flags(KDB_ENABLE_MEM_READ, kdb_cmd_enabled, false)) + return KDB_NOPERM; + /* * Check for internal variables */ @@ -1299,12 +1306,9 @@ static int kdb_local(kdb_reason_t reason, int error, struct pt_regs *regs, *(cmd_hist[cmd_head]) = '\0'; do_full_getstr: -#if defined(CONFIG_SMP) + /* PROMPT can only be set if we have MEM_READ permission. */ snprintf(kdb_prompt_str, CMD_BUFLEN, kdbgetenv("PROMPT"), raw_smp_processor_id()); -#else - snprintf(kdb_prompt_str, CMD_BUFLEN, kdbgetenv("PROMPT")); -#endif if (defcmd_in_progress) strncat(kdb_prompt_str, "[defcmd]", CMD_BUFLEN); -- 2.43.0