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=1794329757; b=WFaZxA66oC2AWtPmZzyeiE+sSzPYfRA9AkcBd9Be/9ujy5NUWBCQ+QPVEbmNaYth8/6D ejLbNH1vdVSUp7knNo0Tx/MAxIdaD4omOq46urhjZdr5Kb8A6/116EyktGhHd/aC0cI3b kIe+ToD3dsO7yXpV0LpP0/6Oo8ZlCkja+NWkE6oX0WhrHeoG/sJ3LUoCA5etVZJyp5kwz 4/dG/3BbLoc+wzEp1QgKgn4HKJMw52gvS85Gcn4qQDy4nl4Nd+8m93MdGEF/v2yjRJI93 /0SCK9MxWE0tyVwBQEQlibMu/477XBmri3bfxRjJvXjZmeQnG6EL6Vu6B0bulkMmfkw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794329757; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=cgY8UtvdVRy5MxersiL/lS0knNP5WmHqc1U7opxXJEQ=; b=hWdpc1Un1rlHXL9ijNAryrp7De1GD/ERBprlMnW8EDCF+sw3u8jPKol/RV308iB+3mef OBscUH+ZPOZG0SNQZK555WbzMkkv0FDpwWGTBNSxo3XSWYAI4axCeH/kB33qU2IJyESrv PLGw6aj97YzbzeuiwHYdaqAepIPLst75H+54cE3VGTKRm2Z4hs+n/XXGlCdN8f+7cfS0j 7QjPKqqYwal2NpOEZMvyaI4QH0Hu9Pbf0kT66KPyDhXctLM0XAZJAS8/5r7xSfE8up6pI DSj7X8RfXo7Z/G20XJMhMXqYfZMXwRXm3g5mf+qLQ1q9VOAOsi3tlv3lfOMUWo1iYBA== 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=XA9llpBp; 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 C60ED606A9C2 for ; Tue, 10 Nov 2026 16:55:56 +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=XA9llpBp Received: by smtp.kernel.org (Postfix) with ESMTPSA id B91E21F0089F; Tue, 10 Nov 2026 16:55:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794329756; bh=cgY8UtvdVRy5MxersiL/lS0knNP5WmHqc1U7opxXJEQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=XA9llpBpNSBI8b+ezVhRVJCwMC4Cu2ZnS+fje5zAstXSKUa/vO9Yi3F00f/aK0qja 2aKU0Wk5gd0GVFdnA4x3vXYeu8JvHhLW5+d09ey8hf0CaZiQSQHnjOU99z3gkjl90N RcGdHUuqG6ZXbFkkWyRiA0DdOFZcQMDnjlYjiFgpg9f0SJ7FYTdPUkT/p4Meysysxj 35Q+dMXvhb7f1VJJ7kIO5Vh/w6+EM3qfayTfQcWizYH9UISNPdP7MqyrfwjK1WCH51 SswG6cPbqgaaXCMLWdsUGXPCYPXyeGOVzWyX1oY1BNgT/PcPAUKgq923pFWdpiiqjN tBnNZEU+Bh1kQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Andrey Misiurov , Helge Deller , Sasha Levin Subject: [PATCH 6.6.y] fbdev: core: Initialize modelist in framebuffer_alloc() Date: Tue, 10 Nov 2026 11:55:54 -0500 Message-ID: <20261110165516.2612252-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107053418-failed-6.6-0c9cb9321cb3@kernel.org> References: <20261107053418-failed-6.6-0c9cb9321cb3@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 context because framebuffer_alloc() lacks the info->blank initialization ] Signed-off-by: Sasha Levin --- drivers/video/fbdev/core/fb_info.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/video/fbdev/core/fb_info.c b/drivers/video/fbdev/core/fb_info.c index 4847ebe50d7d7..9b36361bda6e2 100644 --- a/drivers/video/fbdev/core/fb_info.c +++ b/drivers/video/fbdev/core/fb_info.c @@ -42,6 +42,7 @@ 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