From mboxrd@z Thu Jan 1 00:00:00 1970 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 59B781C695; Thu, 2 Jul 2026 16:55:49 +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=1783011350; cv=none; b=gUnFFNdv4YOvbHJitgnGfMBxovcnAeL3pv18kN2rqIN6nGONnZNs5Qenqmw/f4V0ifOjJNFF7JuRfUQljXLdTY1XeXEey3g7o05qs9FW/u7D1EM9nvQTX7mfWSD4D9goRYYzrYHMaknQos2QFBNbbIfne+Dh7boo4XRj5kMErVE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783011350; c=relaxed/simple; bh=ZS3HI1UVxGZjXG527yG0YZRNQNEKHJXIKZY/4YJly5k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mH2ZXoswpZ3CMb1MfSYX/JUGDrKpTLuCRTOQJY1+Uu7wfIfeh8DY0CAEENso+tBr1ytoksB4oVfGXBfJxlU5e5pMM90j6lw1igeGdZJXeuS+nrSg3h1iQ9+ACUVtEGsqlCxXQcKpvyV5CWHhX7wwKnzqZVlVWn95ZD6NdDfc/6U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Ub0lVaMZ; 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="Ub0lVaMZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BFF4D1F000E9; Thu, 2 Jul 2026 16:55:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783011349; bh=V3BDvUgy2rB/BcnftWBlV2r8bWpPOqSeYcEzUUm3p2g=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Ub0lVaMZEcpc3Ir2JIL45n1dTvIoVHNTMOhJTCNmxY/c3wiImC3YwMVYfhi6LdRK2 LmqGJctaE2V2SYCE2CxsIJzdwO6r4OfhRA1WEdh20H4ix9aNBlrmBADsAl0Ca+kZgZ nSalfxIEs8Z/dJB57ub4vGL5ReBoKwlBfHuEpZIA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Wentao Liang , Bartosz Golaszewski Subject: [PATCH 6.18 075/108] pwrseq: core: fix use-after-free in pwrseq_debugfs_seq_next() Date: Thu, 2 Jul 2026 18:21:12 +0200 Message-ID: <20260702155113.667549547@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155112.110058792@linuxfoundation.org> References: <20260702155112.110058792@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Wentao Liang commit 257595adf9dac15ae1edd9d07753fbc576a7583d upstream. pwrseq_debugfs_seq_next() declares 'next' with __free(put_device), which causes put_device() to be called on the returned pointer when the variable goes out of scope. This results in a use-after-free since the seq_file framework receives a pointer whose reference has already been dropped. Simply removing __free(put_device) would fix the UAF but would leak the reference acquired by bus_find_next_device(), as stop() only calls up_read(&pwrseq_sem) and never releases the device reference. Fix this by making the reference counting consistent across all seq_file callbacks, matching the standard pattern used by PCI and SCSI: - start(): use get_device() so it returns a referenced pointer. - next(): explicitly put_device(curr) to release the previous device's reference (no NULL check needed - the seq_file framework only calls next() while the previous return was non-NULL). - stop(): put_device(data) to release the last iterated device's reference, with a NULL guard since stop() may be called with NULL when start() returned NULL or next() reached end-of-sequence. Cc: stable@vger.kernel.org Fixes: 249ebf3f65f8 ("power: sequencing: implement the pwrseq core") Signed-off-by: Wentao Liang Link: https://patch.msgid.link/20260616151049.1705503-1-vulab@iscas.ac.cn Signed-off-by: Bartosz Golaszewski Signed-off-by: Greg Kroah-Hartman --- drivers/power/sequencing/core.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) --- a/drivers/power/sequencing/core.c +++ b/drivers/power/sequencing/core.c @@ -990,8 +990,9 @@ static void *pwrseq_debugfs_seq_start(st ctx.index = *pos; /* - * We're holding the lock for the entire printout so no need to fiddle - * with device reference count. + * Hold the lock for the entire printout to prevent device removal. + * Reference counts are managed by start()/next()/stop() as required + * by the seq_file contract. */ down_read(&pwrseq_sem); @@ -999,7 +1000,7 @@ static void *pwrseq_debugfs_seq_start(st if (!ctx.index) return NULL; - return ctx.dev; + return get_device(ctx.dev); } static void *pwrseq_debugfs_seq_next(struct seq_file *seq, void *data, @@ -1009,8 +1010,9 @@ static void *pwrseq_debugfs_seq_next(str ++*pos; - struct device *next __free(put_device) = - bus_find_next_device(&pwrseq_bus, curr); + struct device *next = bus_find_next_device(&pwrseq_bus, curr); + + put_device(curr); return next; } @@ -1059,6 +1061,8 @@ static int pwrseq_debugfs_seq_show(struc static void pwrseq_debugfs_seq_stop(struct seq_file *seq, void *data) { + if (data) + put_device(data); up_read(&pwrseq_sem); }