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 299B23191D6; Fri, 7 Aug 2026 14:25:26 +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=1786112728; cv=none; b=elVWuLWAYWbMWlCfKsnK2fpGQg3T1eGAd6pJKOoC6iKhJilha3sdGNWcDCeRjnSCJG0Tj5jAZrCJGA6PsqdejR1PkJPP2q8vHaiJbE8TfKi0le7mk93dZkcKeOLVplsHCSInPXQx+2S3JUmzsY/axAVeFczFEovg7SGW05PARBE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786112728; c=relaxed/simple; bh=6uB8OWGDpym6y9oJ5qxsX//ZJFpXKbzjj/VL1bHouGI=; h=From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type:Date; b=Pmdo/m/StBM5rz3uuZSYx6QsdeomcRZ9LNKi9ujb23bYGh/WTDv8Rp1Q9DPs0Ms2iKiHMD+8xWLaxtvSzbwAtzbqRcXODEwZEiXEDrj1XZ7y1gGh2UPBfqcTfcXqpLE80OaUdslycdUURcAexGEqjpr8RNykkiUHzAtoQHnYHUk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WsGoffZ9; 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="WsGoffZ9" Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id 796871F000E9; Fri, 7 Aug 2026 14:25:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786112726; bh=P2Hsg1cdmQwQMSFF8/2gaSQ0nlfQSkMtLeSn0RlCfJM=; h=From:To:Cc:Subject:Date; b=WsGoffZ9aRBHc/D9e3a1UTjFZYbEVYEIVd33nFgJWvd05XbSdyLb6Dhwfn+kVcNTf zdmnP66eQU0wvkkxbwexWodc7a4kTGZoAirDmIZp97GIaizl1aQrjv5H5JhUmN1UpE VfVvSrxPl1SUEaBwJ145jtfDAFlTzr5lEN2QswfT06kfkZA/nzXJpf8d7pV/Fjhm0M 5zq2N3/nDyfEmSGAp+HEl+MW7DtXlS2388nS4Ab/lvhdF/eJByTEhB1V561JkEv5Wi MrPmsuVkJqUmHFl6f2XVUNjyztpd2+8OQdy9jgMernNq0YwJnQ3PMlaHhFyFYPbPzI N4f6x5A5KnTZg== From: "syzbot" To: syzkaller-bugs@googlegroups.com, Aleksandr Nogikh , , "Takashi Sakamoto" Cc: linux-kernel@vger.kernel.org, syzbot@lists.linux.dev Subject: [PATCH] firewire: ohci: fix NULL pointer dereference in ar_context_release Message-ID: <90c5db71-dd1f-4d46-b9d3-2f1046cbd5ea@mail.kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Date: Fri, 7 Aug 2026 14:25:26 +0000 (UTC) From: Aleksandr Nogikh During the error handling path of the driver's probe function, a NULL pointer dereference can occur in ar_context_release(). When pci_probe() fails early (e.g., if pcim_enable_device() or MMIO mapping fails), the devres cleanup mechanism invokes release_ohci(). This function unconditionally calls ar_context_release() to clean up the asynchronous receive contexts. However, if ar_context_init() was not yet called, ctx->ohci remains NULL (as the fw_ohci structure is zero-initialized by devres_alloc()). ar_context_release() immediately dereferences ctx->ohci to get the dev pointer before checking if the context was actually initialized, leading to a crash: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] RIP: 0010:ar_context_release+0x3f/0x380 drivers/firewire/ohci.c:543 Call Trace: release_ohci+0x3f/0x60 drivers/firewire/ohci.c:3567 release_nodes drivers/base/devres.c:546 [inline] devres_release_all+0x1a8/0x260 drivers/base/devres.c:576 device_unbind_cleanup drivers/base/dd.c:597 [inline] really_probe+0x451/0xae0 drivers/base/dd.c:772 To fix this, move the assignment of the dev pointer after the !ctx->buffer check. If ctx->buffer is NULL, it indicates that the context was never successfully initialized and there is nothing to release, safely avoiding the dereference of the uninitialized ctx->ohci pointer. Fixes: 5716e58aecdd ("firewire: ohci: release buffer for AR req/resp contexts when managed resource is released") Assisted-by: Gemini:gemini-3.5-flash Gemini:gemini-3.1-pro-preview syzbot Reported-by: syzbot+d30aad27833a559defab@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d30aad27833a559defab Link: https://syzkaller.appspot.com/ai_job?id=10a18617-7893-42dd-bf1c-cd49e19e95d9 Signed-off-by: Aleksandr Nogikh --- diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index 8153d62c5..e947227e0 100644 --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -540,11 +540,13 @@ static void ar_context_link_page(struct ar_context *ctx, unsigned int index) static void ar_context_release(struct ar_context *ctx) { - struct device *dev = ctx->ohci->card.device; + struct device *dev; if (!ctx->buffer) return; + dev = ctx->ohci->card.device; + for (int i = 0; i < AR_BUFFERS; ++i) { dma_addr_t dma_addr = ctx->dma_addrs[i]; if (dma_addr) base-commit: 075b74841bd0065a3bda3440873c747938e69b68 -- See https://goo.gle/syzbot-ai-patches for information about AI-generated patches. The person who has signed off on the patch is responsible for addressing comments. syzbot engineers can be reached at syzkaller@googlegroups.com.