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 3AA2A2AE68; Tue, 26 Aug 2025 14:41:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756219302; cv=none; b=CIqv6kUmUa34FcwPltJ0gKJrNzfOiSoUOvurZVcEWIEB5u+crmgRCu2CaR6rxtsCFH+B3CcSrAtU29Muj6AU7uhN+923Bm7Kbw2aGEgHOsub2oqU02NwA36cXh7eADQW9IgAMkuKqKfZAB4zvaezTnMPtfXjzZ2s7Jxb/XVRcPk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756219302; c=relaxed/simple; bh=lI9/RD0nY3sPtGNsRcd94Tb7+s+mv+SIRWvtLblFhXU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OdkQxuEaZWGiF/RGc5OyAsSAbekSftVsM6hJaQ3tJCgaZLjg2GGvdnUq3MYe66PsQapRvXN7Pi1HZqHfCbrEtZqfhm5/6giwq/+eO4NvNocZhgumHRnJIpMv6J4tUxs/w1GTgEPwC4dpcXC1WViko9nJafjLw/1UimkOyDp36Lw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=dale/yu4; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="dale/yu4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1DC1C4CEF1; Tue, 26 Aug 2025 14:41:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756219302; bh=lI9/RD0nY3sPtGNsRcd94Tb7+s+mv+SIRWvtLblFhXU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dale/yu4a/umz6Ou8aPdaKfCTR1HZCP5WsKQtyAftu8yA70BmkSCGQjU3WIuw9gAZ Mw7/rGjIjQK3CSoyXO6+cQWwk0x64C2NZHFPG9Vx+Rf/L5ElyId/pKTPmR1uC22/Ae uBZVILpqt9g+lcppFYrs9vwRJdhN/drxqli5N1H0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+d6995b62e5ac7d79557a@syzkaller.appspotmail.com, Ian Abbott Subject: [PATCH 5.4 330/403] comedi: Fail COMEDI_INSNLIST ioctl if n_insns is too large Date: Tue, 26 Aug 2025 13:10:56 +0200 Message-ID: <20250826110915.948695235@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250826110905.607690791@linuxfoundation.org> References: <20250826110905.607690791@linuxfoundation.org> User-Agent: quilt/0.68 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 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ian Abbott [ Upstream commit 08ae4b20f5e82101d77326ecab9089e110f224cc ] The handling of the `COMEDI_INSNLIST` ioctl allocates a kernel buffer to hold the array of `struct comedi_insn`, getting the length from the `n_insns` member of the `struct comedi_insnlist` supplied by the user. The allocation will fail with a WARNING and a stack dump if it is too large. Avoid that by failing with an `-EINVAL` error if the supplied `n_insns` value is unreasonable. Define the limit on the `n_insns` value in the `MAX_INSNS` macro. Set this to the same value as `MAX_SAMPLES` (65536), which is the maximum allowed sum of the values of the member `n` in the array of `struct comedi_insn`, and sensible comedi instructions will have an `n` of at least 1. Reported-by: syzbot+d6995b62e5ac7d79557a@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d6995b62e5ac7d79557a Fixes: ed9eccbe8970 ("Staging: add comedi core") Tested-by: Ian Abbott Cc: stable@vger.kernel.org # 5.13+ Signed-off-by: Ian Abbott Link: https://lore.kernel.org/r/20250704120405.83028-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman [ Reworked for before commit bac42fb21259 ("comedi: get rid of compat_alloc_user_space() mess in COMEDI_CMD{,TEST} compat") ] Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- v2: Fixed a build error due to applying a fixup to the wrong commit. Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/comedi_compat32.c | 3 +++ drivers/staging/comedi/comedi_fops.c | 13 +++++++++++++ 2 files changed, 16 insertions(+) --- a/drivers/staging/comedi/comedi_compat32.c +++ b/drivers/staging/comedi/comedi_compat32.c @@ -360,6 +360,9 @@ static int compat_insnlist(struct file * if (err) return -EFAULT; + if (n_insns > 65536) /* See MAX_INSNS in comedi_fops.c */ + return -EINVAL; + /* Allocate user memory to copy insnlist and insns into. */ s = compat_alloc_user_space(offsetof(struct combined_insnlist, insn[n_insns])); --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1519,6 +1519,16 @@ out: return ret; } +#define MAX_INSNS 65536 +static int check_insnlist_len(struct comedi_device *dev, unsigned int n_insns) +{ + if (n_insns > MAX_INSNS) { + dev_dbg(dev->class_dev, "insnlist length too large\n"); + return -EINVAL; + } + return 0; +} + /* * COMEDI_INSNLIST ioctl * synchronous instruction list @@ -1551,6 +1561,9 @@ static int do_insnlist_ioctl(struct come if (copy_from_user(&insnlist, arg, sizeof(insnlist))) return -EFAULT; + ret = check_insnlist_len(dev, insnlist.n_insns); + if (ret) + return ret; insns = kcalloc(insnlist.n_insns, sizeof(*insns), GFP_KERNEL); if (!insns) { ret = -ENOMEM;