From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794331293; b=QTEhgmvAuFMC2ro+WinFba0s3gVhk8oDKqmXe+qdhWhiMzJKFzpewn1oS771FR4ORgFp d+7Gw5pHdH1bpOrZfGxhdblE2vv/FvOn9WLDkUpYWc5oMYWmvEgUQ4YR53aCkjb2jF4DT idt24zviQ0QfI5e5oBsIKHn+gkfG/vZqoQ3x8oNwYidBxu+XHX8MSPzh+0F9XI/yQH1hL jZjliGn1ZXoGIW5GPoAnxq8qYrygUHOjw5YK/jQCkg6a6O/y6s4q7nuVgjyg3TCSxGZbO hOnCZtzEt6tAbqc74nC8iWganOPgRa4VarBMeZJhSaJ3CLxHA3TSGvl+eDklWvZTzcA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794331293; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=IBJLW9gJYjVVTmSaQ4sa3ZZvNhNV2rgDrr2kJyOrSs0=; b=qEHdO4btiq5LehNUSznXraufw380eak9dYO4qvRrpuAQAOPkpiEAtOWDm4TzwR+zhasd 7GKmapC7Vdsu6o10xfYUNpuhCpgCtymzrBqx7kuPwXUyfkDQAj7EqhwmScEzsaz14EE2A ccXJpCp5AqQLby3pLwcWycW0PSpqAEOd5nvyldN3asUOi6SfN0DIHiz1wmxX/a1gEGFc5 kqUc/80j8jh+Hc7TKOO9Uq2ueF30GmJX5dfOtoX0luXM+ggeyDrQ82h4xTTmpUT8r8zvU C+JbvgGpzEWNVDQXnT/tmUexIaVZpZPYv0yTrvnE0WTS2rYs/dS+qUDCKFZzA6HzcIQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="Y5qq/gct"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E26A3606A31C for ; Tue, 10 Nov 2026 17:21:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Y5qq/gct Received: by smtp.kernel.org (Postfix) with ESMTPSA id D27491F0089F; Tue, 10 Nov 2026 17:21:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794331292; bh=IBJLW9gJYjVVTmSaQ4sa3ZZvNhNV2rgDrr2kJyOrSs0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Y5qq/gctqdDOqq2xEwBqfkKDvi+v6Lkst53m+tDKE3BE9EjRS6UVWQDIOgcyd2qZV gfgWZATMRs5ANUcQ8zqYVNf/YaT9cbN8raxljTIWlOHli+9QpQRTgtcLwyB6QGnv13 brnFKooO9ixdK+G9y5/YrrZIRGmYqMqyDrvhiubWZF4jLE36naGb0WSGvvfUUTUXX8 yI1PcYM0IxOx1cVoUoDiUVqlAXyJjcQM/VyEgJ5xNN+go1E810VHDGBTocTrJd7xBy IpTOKADwIUY3RR00zUGOCm22Kje7S1b9cxh/0Fcip7eSewM1F4LG+1QF/YgLvKbkCr W6/Kit5rfMzig== From: Sasha Levin To: stable@vger.kernel.org Cc: Andrey Misiurov , Helge Deller , Sasha Levin Subject: [PATCH 5.15.y] fbdev: core: Initialize modelist in framebuffer_alloc() Date: Tue, 10 Nov 2026 12:21:30 -0500 Message-ID: <20261110172104.2893386-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107060515-failed-5.15-0c9cb9321cb3@kernel.org> References: <20261107060515-failed-5.15-0c9cb9321cb3@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Andrey Misiurov [ Upstream commit 0c9cb9321cb3863b52bdea4b8ae5a27705762c9e ] framebuffer_alloc() returns zeroed memory, so info->modelist starts out with NULL next and prev pointers. The list head is initialized only later, by fb_videomode_to_modelist() or by do_register_framebuffer(). The "fix potential memory leak" commits listed below added fb_destroy_modelist(&info->modelist) to the probe error paths of s3fb, tdfxfb, tridentfb, i740fb and carminefb. These paths can run before the list head is initialized: - s3fb, tdfxfb, tridentfb and i740fb call fb_videomode_to_modelist() only after a successful EDID read, and tridentfb can also hit the error path on an ioremap() or kmalloc() failure before that; - carminefb jumps to the error path when fb_find_mode() fails, before its fb_videomode_to_modelist() call. fb_destroy_modelist() then dereferences the NULL head. Reproduced on Debian 12 (6.1.180) by binding s3fb to a VGA device without EDID and forcing fb_alloc_cmap() to fail: s3fb 0000:00:03.0: cannot allocate colormap BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:fb_destroy_modelist+0x10/0x80 Call Trace: s3_pci_probe.cold+0x12b/0x2bf [s3fb] local_pci_probe+0x41/0x80 pci_device_probe+0xc3/0x240 really_probe+0xde/0x380 __driver_probe_device+0x84/0x150 driver_probe_device+0x1f/0x90 __driver_attach+0xce/0x1c0 bus_for_each_dev+0x87/0xd0 bus_add_driver+0x1ae/0x200 driver_register+0x89/0xe0 do_one_initcall+0x59/0x220 do_init_module+0x4a/0x1f0 Initialize the list head in framebuffer_alloc(), so info->modelist is always a valid, possibly empty, list and fb_destroy_modelist() is safe on every error path. Keep the lazy initialization in do_register_framebuffer(), as drivers that embed struct fb_info rather than calling framebuffer_alloc() still depend on it. Fixes: 3b0ed04bc852 ("fbdev: s3fb: fix potential memory leak in s3_pci_probe()") Fixes: bb019d755366 ("fbdev: tdfxfb: fix potential memory leak in tdfxfb_probe()") Fixes: 7a35ec619d9a ("fbdev: tridentfb: fix potential memory leak in trident_pci_probe()") Fixes: 5936063409af ("fbdev: i740fb: fix potential memory leak in i740fb_probe()") Fixes: 6fcca16a2b19 ("fbdev: carminefb: fix potential memory leak in alloc_carmine_fb()") Cc: stable@vger.kernel.org Signed-off-by: Andrey Misiurov Signed-off-by: Helge Deller [ sashal: adjusted framebuffer_alloc() context due to the missing info->blank assignment ] Signed-off-by: Sasha Levin --- drivers/video/fbdev/core/fbsysfs.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c index 09ee27e7fc25f..1117127402e82 100644 --- a/drivers/video/fbdev/core/fbsysfs.c +++ b/drivers/video/fbdev/core/fbsysfs.c @@ -56,6 +56,7 @@ struct fb_info *framebuffer_alloc(size_t size, struct device *dev) info->device = dev; info->fbcon_rotate_hint = -1; + INIT_LIST_HEAD(&info->modelist); #if IS_ENABLED(CONFIG_FB_BACKLIGHT) mutex_init(&info->bl_curve_mutex); -- 2.53.0