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 4C7B158F070 for ; Tue, 8 Sep 2026 17:55:47 +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=1788890148; cv=none; b=FeR96Fn/E7WFGXhL1KX2y4F3VJPaCylsgiiwV59uskWJmCnD1KOIMrN/7e5U1n6j+SazEsU9Dbubx24HlbID87g/KAG6pumu7LsxFVlAwcxFu02cdptInq3U0o29djlwBUvi1MWqwvYEFEz06AZ6sfLwNT+SfFNXkiZ3K5FtQUc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788890148; c=relaxed/simple; bh=uOnpGB1EjY92DLzG5VdI0mv22ORBDIgXGtYLy/YtsR0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iYMtDrfU8q79C0TfDctG5+XGmzAf161o0+Wv140cJQTmw4Y1NKRZRAp/0ZccVNsw9bwSc4CpIvToMfk7T63iNv9crmDs+lEo58oLujqLgxkJg2Mex+YHWkBnv46n4JqHSaqoousl1xo5KHCnB3vTdDZE+ZX3Tul10jbU79qwnzc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bfXjvvWf; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bfXjvvWf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 826DA1F00A3D; Tue, 8 Sep 2026 17:55:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788890147; bh=B8R6HfQwTnr40kg9N6vTgVC1Kg+vdh7WO5m6+qxEDnc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bfXjvvWfEkqKZL8CoRzw7YTKXdDL5FJG7xdDp26Jfk8fbiGtd3jUVwGDsmeU+LQAf H7lQtjJmyM4FGAYT6Wq1TY8SmN+mfuxXs2LKnYT8P8lCDxOkHgnqUIX8Ey3cfSqxhe RDvCM5F0GkbOK19IAb6uvuxccpMkS4ML+TVhl/rdfnhhsHiSdA++c+ztrUPfX14QYF jF3CMYqv3AOM143EDLouzkZ5QP3EG8hSWMlFbCtc7oaRzRttnpxANT4lwpV2NOIt6w XHuXdegZ41vOX5oGWMlocZuhd9luCqpfDP3HyUXEyeiQBWy1bSarMry4bFu5Ce7y/0 8eZmxCraJwi5A== From: Sasha Levin To: stable@vger.kernel.org Cc: Jiacheng Yu , Petr Pavlu , Sasha Levin Subject: [PATCH 6.6.y 5/5] params: fix charp corruption on allocation failure Date: Tue, 8 Sep 2026 13:55:41 -0400 Message-ID: <20260908175541.151692-5-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260908175541.151692-1-sashal@kernel.org> References: <2026090331-stays-casually-f049@gregkh> <20260908175541.151692-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jiacheng Yu [ Upstream commit 3dfaae04243cde460d82dfc2a7dd0bb6664d20ae ] param_set_charp() stores charp parameters in allocated memory after slab is available, and releases the previous value when the parameter is updated. The previous value is released before the replacement allocation succeeds. If kmalloc_parameter() fails, the setter returns -ENOMEM with the parameter left as NULL. Failing zswap's compressor update before zswap is initialized can later trigger: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:strcmp+0x10/0x30 Call Trace: zswap_setup+0x3b1/0x490 zswap_enabled_param_set+0x5b/0xa0 param_attr_store+0x93/0xe0 module_attr_store+0x1c/0x30 kernfs_fop_write_iter+0x116/0x1f0 Allocate and copy the replacement first, then replace the parameter value only after allocation succeeds. Fixes: e180a6b7759a ("param: fix charp parameters set via sysfs") Cc: stable@vger.kernel.org Signed-off-by: Jiacheng Yu Reviewed-by: Petr Pavlu Signed-off-by: Petr Pavlu Signed-off-by: Sasha Levin --- kernel/params.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/kernel/params.c b/kernel/params.c index f6d11831749be..12fb187ebf63e 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -265,6 +265,7 @@ EXPORT_SYMBOL_GPL(param_set_uint_minmax); int param_set_charp(const char *val, const struct kernel_param *kp) { + char *tmp; size_t len, maxlen = 1024; len = strnlen(val, maxlen + 1); @@ -273,19 +274,20 @@ int param_set_charp(const char *val, const struct kernel_param *kp) return -ENOSPC; } - maybe_kfree_parameter(*(char **)kp->arg); - /* * This is a hack. We can't kmalloc() in early boot, and we * don't need to; this mangled commandline is preserved. */ if (slab_is_available()) { - *(char **)kp->arg = kmalloc_parameter(len + 1); - if (!*(char **)kp->arg) + tmp = kmalloc_parameter(len + 1); + if (!tmp) return -ENOMEM; - strcpy(*(char **)kp->arg, val); + memcpy(tmp, val, len + 1); } else - *(const char **)kp->arg = val; + tmp = (char *)val; + + maybe_kfree_parameter(*(char **)kp->arg); + *(char **)kp->arg = tmp; return 0; } -- 2.53.0