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 4CD01746A for ; Thu, 12 Jan 2023 14:01:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3CDABC433D2; Thu, 12 Jan 2023 14:01:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673532111; bh=HPmIDxaoMR6U9pgJ5s3dbnjhjWZLgiwkRCFGedtKinE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H+HSqOASzr3QAxLRoRioHqThwo+kXcLgOq5nYIddeUSg2IkAY2NHzIg6/Z+FAGqlg AzTXq37mMZyhcxJtEZXw2/a7Ne3EwKeEfB2LSYYbE8VLQ6BWY2ZFqlH6HmlV/7dirN Pj5fPXqJsZYRG24OFUuYtTPShv6xacmFb0Y+BHho= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Gaosheng Cui , Andrew Morton , Sasha Levin Subject: [PATCH 5.10 056/783] lib/fonts: fix undefined behavior in bit shift for get_default_font Date: Thu, 12 Jan 2023 14:46:12 +0100 Message-Id: <20230112135526.732509712@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230112135524.143670746@linuxfoundation.org> References: <20230112135524.143670746@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Gaosheng Cui [ Upstream commit 6fe888c4d2fb174408e4540bb2d5602b9f507f90 ] Shifting signed 32-bit value by 31 bits is undefined, so changing significant bit to unsigned. The UBSAN warning calltrace like below: UBSAN: shift-out-of-bounds in lib/fonts/fonts.c:139:20 left shift of 1 by 31 places cannot be represented in type 'int' dump_stack_lvl+0x7d/0xa5 dump_stack+0x15/0x1b ubsan_epilogue+0xe/0x4e __ubsan_handle_shift_out_of_bounds+0x1e7/0x20c get_default_font+0x1c7/0x1f0 fbcon_startup+0x347/0x3a0 do_take_over_console+0xce/0x270 do_fbcon_takeover+0xa1/0x170 do_fb_registered+0x2a8/0x340 fbcon_fb_registered+0x47/0xe0 register_framebuffer+0x294/0x4a0 __drm_fb_helper_initial_config_and_unlock+0x43c/0x880 [drm_kms_helper] drm_fb_helper_initial_config+0x52/0x80 [drm_kms_helper] drm_fbdev_client_hotplug+0x156/0x1b0 [drm_kms_helper] drm_fbdev_generic_setup+0xfc/0x290 [drm_kms_helper] bochs_pci_probe+0x6ca/0x772 [bochs] local_pci_probe+0x4d/0xb0 pci_device_probe+0x119/0x320 really_probe+0x181/0x550 __driver_probe_device+0xc6/0x220 driver_probe_device+0x32/0x100 __driver_attach+0x195/0x200 bus_for_each_dev+0xbb/0x120 driver_attach+0x27/0x30 bus_add_driver+0x22e/0x2f0 driver_register+0xa9/0x190 __pci_register_driver+0x90/0xa0 bochs_pci_driver_init+0x52/0x1000 [bochs] do_one_initcall+0x76/0x430 do_init_module+0x61/0x28a load_module+0x1f82/0x2e50 __do_sys_finit_module+0xf8/0x190 __x64_sys_finit_module+0x23/0x30 do_syscall_64+0x58/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Link: https://lkml.kernel.org/r/20221031113829.4183153-1-cuigaosheng1@huawei.com Fixes: c81f717cb9e0 ("fbcon: Fix typo and bogus logic in get_default_font") Signed-off-by: Gaosheng Cui Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- lib/fonts/fonts.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/fonts/fonts.c b/lib/fonts/fonts.c index 5f4b07b56cd9..973866438608 100644 --- a/lib/fonts/fonts.c +++ b/lib/fonts/fonts.c @@ -135,8 +135,8 @@ const struct font_desc *get_default_font(int xres, int yres, u32 font_w, if (res > 20) c += 20 - res; - if ((font_w & (1 << (f->width - 1))) && - (font_h & (1 << (f->height - 1)))) + if ((font_w & (1U << (f->width - 1))) && + (font_h & (1U << (f->height - 1)))) c += 1000; if (c > cc) { -- 2.35.1