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 DAC32374EA; Mon, 10 Mar 2025 18:19:49 +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=1741630790; cv=none; b=BwKpcIbrdpfLoYotWyKwfFmdSbWZj7J6OXSKc0maSiasFJmEqLGN6b/9IL0ElK0uECqx/6OmuVTY6Hs606+zyOMZB/vidAGeKi5ok3HBEwy4Lhw9XKNsA4DPAvsksBtRfA1IJz5WVSuPV+RY0ReXCV+I5oVoGkpmo+u9UuU2548= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741630790; c=relaxed/simple; bh=ipl4XrT52pFNmdDL1RAaCUZ65R8wd5kP5CIlAMFc+Uo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ahrYxkT/0a7GaZGgHLIZFpcmBcq4Igk1p5QdHL9WO0mqnJPvzAytYzp8K9MUomnajzfuvo6jJ4GqJ9pSbd6bkRgXuUsO26VP6ijorKJvM6f37haaKPL+Ms1F5fX+3gmTvbcqKZAjc4TY/oZ5wOjtUZ6BmWjylH5Pl+GWuJnqN28= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Kfq2N6wO; 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="Kfq2N6wO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63EE2C4CEE5; Mon, 10 Mar 2025 18:19:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1741630789; bh=ipl4XrT52pFNmdDL1RAaCUZ65R8wd5kP5CIlAMFc+Uo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Kfq2N6wOrJ9EJA/cfy5Hjmx64z3RbrFdjgqxa//ZWy9mdcjFS9CED8Wh9FDaMJtL0 BCYqVOsF7DhXV+CJ1Zs8WeRyZONkbFWO0QX1HnCuBpwQdf1D9TnIk8tu/iGl25gUbM Z2s0k1VoJ/Ot0g1U9R3LvnWm2f0n6EvmrIp9V/DM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Koichiro Den , Bartosz Golaszewski Subject: [PATCH 5.15 536/620] gpio: aggregator: protect driver attr handlers against module unload Date: Mon, 10 Mar 2025 18:06:22 +0100 Message-ID: <20250310170606.698613575@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250310170545.553361750@linuxfoundation.org> References: <20250310170545.553361750@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Koichiro Den commit 12f65d1203507f7db3ba59930fe29a3b8eee9945 upstream. Both new_device_store and delete_device_store touch module global resources (e.g. gpio_aggregator_lock). To prevent race conditions with module unload, a reference needs to be held. Add try_module_get() in these handlers. For new_device_store, this eliminates what appears to be the most dangerous scenario: if an id is allocated from gpio_aggregator_idr but platform_device_register has not yet been called or completed, a concurrent module unload could fail to unregister/delete the device, leaving behind a dangling platform device/GPIO forwarder. This can result in various issues. The following simple reproducer demonstrates these problems: #!/bin/bash while :; do # note: whether 'gpiochip0 0' exists or not does not matter. echo 'gpiochip0 0' > /sys/bus/platform/drivers/gpio-aggregator/new_device done & while :; do modprobe gpio-aggregator modprobe -r gpio-aggregator done & wait Starting with the following warning, several kinds of warnings will appear and the system may become unstable: ------------[ cut here ]------------ list_del corruption, ffff888103e2e980->next is LIST_POISON1 (dead000000000100) WARNING: CPU: 1 PID: 1327 at lib/list_debug.c:56 __list_del_entry_valid_or_report+0xa3/0x120 [...] RIP: 0010:__list_del_entry_valid_or_report+0xa3/0x120 [...] Call Trace: ? __list_del_entry_valid_or_report+0xa3/0x120 ? __warn.cold+0x93/0xf2 ? __list_del_entry_valid_or_report+0xa3/0x120 ? report_bug+0xe6/0x170 ? __irq_work_queue_local+0x39/0xe0 ? handle_bug+0x58/0x90 ? exc_invalid_op+0x13/0x60 ? asm_exc_invalid_op+0x16/0x20 ? __list_del_entry_valid_or_report+0xa3/0x120 gpiod_remove_lookup_table+0x22/0x60 new_device_store+0x315/0x350 [gpio_aggregator] kernfs_fop_write_iter+0x137/0x1f0 vfs_write+0x262/0x430 ksys_write+0x60/0xd0 do_syscall_64+0x6c/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7e [...] ---[ end trace 0000000000000000 ]--- Fixes: 828546e24280 ("gpio: Add GPIO Aggregator") Cc: stable@vger.kernel.org Signed-off-by: Koichiro Den Link: https://lore.kernel.org/r/20250224143134.3024598-2-koichiro.den@canonical.com Signed-off-by: Bartosz Golaszewski Signed-off-by: Greg Kroah-Hartman --- drivers/gpio/gpio-aggregator.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) --- a/drivers/gpio/gpio-aggregator.c +++ b/drivers/gpio/gpio-aggregator.c @@ -116,10 +116,15 @@ static ssize_t new_device_store(struct d struct platform_device *pdev; int res, id; + if (!try_module_get(THIS_MODULE)) + return -ENOENT; + /* kernfs guarantees string termination, so count + 1 is safe */ aggr = kzalloc(sizeof(*aggr) + count + 1, GFP_KERNEL); - if (!aggr) - return -ENOMEM; + if (!aggr) { + res = -ENOMEM; + goto put_module; + } memcpy(aggr->args, buf, count + 1); @@ -158,6 +163,7 @@ static ssize_t new_device_store(struct d } aggr->pdev = pdev; + module_put(THIS_MODULE); return count; remove_table: @@ -172,6 +178,8 @@ free_table: kfree(aggr->lookups); free_ga: kfree(aggr); +put_module: + module_put(THIS_MODULE); return res; } @@ -200,13 +208,19 @@ static ssize_t delete_device_store(struc if (error) return error; + if (!try_module_get(THIS_MODULE)) + return -ENOENT; + mutex_lock(&gpio_aggregator_lock); aggr = idr_remove(&gpio_aggregator_idr, id); mutex_unlock(&gpio_aggregator_lock); - if (!aggr) + if (!aggr) { + module_put(THIS_MODULE); return -ENOENT; + } gpio_aggregator_free(aggr); + module_put(THIS_MODULE); return count; } static DRIVER_ATTR_WO(delete_device);