Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756103AbbGaUyw (ORCPT ); Fri, 31 Jul 2015 16:54:52 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:47737 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754771AbbGaUTV (ORCPT ); Fri, 31 Jul 2015 16:19:21 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Fries , Thorsten Bschorr , Evgeniy Polyakov Subject: [PATCH 4.1 167/267] w1_therm reference count family data Date: Fri, 31 Jul 2015 12:40:18 -0700 Message-Id: <20150731194007.542521190@linuxfoundation.org> X-Mailer: git-send-email 2.5.0 In-Reply-To: <20150731194001.933895871@linuxfoundation.org> References: <20150731194001.933895871@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4380 Lines: 150 4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Fries commit f7134eea05b2fb4a2c0935f8a540539fff01f3eb upstream. A temperature conversion can take 750 ms and when possible the w1_therm slave driver drops the bus_mutex to allow other bus operations, but that includes operations such as a periodic slave search, which can remove this slave when it is no longer detected. If that happens the sl->family_data will be freed and set to NULL causing w1_slave_show to crash when it wakes up. Signed-off-by: David Fries Reported-By: Thorsten Bschorr Tested-by: Thorsten Bschorr Acked-by: Evgeniy Polyakov Signed-off-by: Greg Kroah-Hartman --- drivers/w1/slaves/w1_therm.c | 62 ++++++++++++++++++++++++++++++++----------- 1 file changed, 47 insertions(+), 15 deletions(-) --- a/drivers/w1/slaves/w1_therm.c +++ b/drivers/w1/slaves/w1_therm.c @@ -59,16 +59,32 @@ MODULE_ALIAS("w1-family-" __stringify(W1 static int w1_strong_pullup = 1; module_param_named(strong_pullup, w1_strong_pullup, int, 0); +struct w1_therm_family_data { + uint8_t rom[9]; + atomic_t refcnt; +}; + +/* return the address of the refcnt in the family data */ +#define THERM_REFCNT(family_data) \ + (&((struct w1_therm_family_data*)family_data)->refcnt) + static int w1_therm_add_slave(struct w1_slave *sl) { - sl->family_data = kzalloc(9, GFP_KERNEL); + sl->family_data = kzalloc(sizeof(struct w1_therm_family_data), + GFP_KERNEL); if (!sl->family_data) return -ENOMEM; + atomic_set(THERM_REFCNT(sl->family_data), 1); return 0; } static void w1_therm_remove_slave(struct w1_slave *sl) { + int refcnt = atomic_sub_return(1, THERM_REFCNT(sl->family_data)); + while(refcnt) { + msleep(1000); + refcnt = atomic_read(THERM_REFCNT(sl->family_data)); + } kfree(sl->family_data); sl->family_data = NULL; } @@ -194,13 +210,22 @@ static ssize_t w1_slave_show(struct devi struct w1_slave *sl = dev_to_w1_slave(device); struct w1_master *dev = sl->master; u8 rom[9], crc, verdict, external_power; - int i, max_trying = 10; + int i, ret, max_trying = 10; ssize_t c = PAGE_SIZE; + u8 *family_data = sl->family_data; + + ret = mutex_lock_interruptible(&dev->bus_mutex); + if (ret != 0) + goto post_unlock; - i = mutex_lock_interruptible(&dev->bus_mutex); - if (i != 0) - return i; + if(!sl->family_data) + { + ret = -ENODEV; + goto pre_unlock; + } + /* prevent the slave from going away in sleep */ + atomic_inc(THERM_REFCNT(family_data)); memset(rom, 0, sizeof(rom)); while (max_trying--) { @@ -230,17 +255,19 @@ static ssize_t w1_slave_show(struct devi mutex_unlock(&dev->bus_mutex); sleep_rem = msleep_interruptible(tm); - if (sleep_rem != 0) - return -EINTR; + if (sleep_rem != 0) { + ret = -EINTR; + goto post_unlock; + } - i = mutex_lock_interruptible(&dev->bus_mutex); - if (i != 0) - return i; + ret = mutex_lock_interruptible(&dev->bus_mutex); + if (ret != 0) + goto post_unlock; } else if (!w1_strong_pullup) { sleep_rem = msleep_interruptible(tm); if (sleep_rem != 0) { - mutex_unlock(&dev->bus_mutex); - return -EINTR; + ret = -EINTR; + goto pre_unlock; } } @@ -269,19 +296,24 @@ static ssize_t w1_slave_show(struct devi c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n", crc, (verdict) ? "YES" : "NO"); if (verdict) - memcpy(sl->family_data, rom, sizeof(rom)); + memcpy(family_data, rom, sizeof(rom)); else dev_warn(device, "Read failed CRC check\n"); for (i = 0; i < 9; ++i) c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", - ((u8 *)sl->family_data)[i]); + ((u8 *)family_data)[i]); c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n", w1_convert_temp(rom, sl->family->fid)); + ret = PAGE_SIZE - c; + +pre_unlock: mutex_unlock(&dev->bus_mutex); - return PAGE_SIZE - c; +post_unlock: + atomic_dec(THERM_REFCNT(family_data)); + return ret; } static int __init w1_therm_init(void) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/