[PATCH 2/2] scsi: ufs: Protect PM ops and err_handler from user access through sysfs

From: Can Guo
Date: Wed Dec 30 2020 - 23:34:28 EST

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User layer may access sysfs nodes when system PM ops or error handling
is running, which can cause various problems. Rename eh_sem to host_sem
and use it to protect PM ops and error handling from user layer intervene.

Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>

diff --git a/drivers/scsi/ufs/ufs-sysfs.c b/drivers/scsi/ufs/ufs-sysfs.c
index 08e72b7..1828b34 100644
--- a/drivers/scsi/ufs/ufs-sysfs.c
+++ b/drivers/scsi/ufs/ufs-sysfs.c
@@ -154,18 +154,29 @@ static ssize_t auto_hibern8_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
u32 ahit;
+ int ret;
struct ufs_hba *hba = dev_get_drvdata(dev);

if (!ufshcd_is_auto_hibern8_supported(hba))
return -EOPNOTSUPP;

+ down(&hba->host_sem);
+ if (hba->shutting_down) {
+ ret = -EBUSY;
+ goto out;
+ }
+
pm_runtime_get_sync(hba->dev);
ufshcd_hold(hba, false);
ahit = ufshcd_readl(hba, REG_AUTO_HIBERNATE_IDLE_TIMER);
ufshcd_release(hba);
pm_runtime_put_sync(hba->dev);

- return scnprintf(buf, PAGE_SIZE, "%d\n", ufshcd_ahit_to_us(ahit));
+ ret = scnprintf(buf, PAGE_SIZE, "%d\n", ufshcd_ahit_to_us(ahit));
+
+out:
+ up(&hba->host_sem);
+ return ret;
}

static ssize_t auto_hibern8_store(struct device *dev,
@@ -174,6 +185,7 @@ static ssize_t auto_hibern8_store(struct device *dev,
{
struct ufs_hba *hba = dev_get_drvdata(dev);
unsigned int timer;
+ int ret = 0;

if (!ufshcd_is_auto_hibern8_supported(hba))
return -EOPNOTSUPP;
@@ -184,9 +196,17 @@ static ssize_t auto_hibern8_store(struct device *dev,
if (timer > UFSHCI_AHIBERN8_MAX)
return -EINVAL;

+ down(&hba->host_sem);
+ if (hba->shutting_down) {
+ ret = -EBUSY;
+ goto out;
+ }
+
ufshcd_auto_hibern8_update(hba, ufshcd_us_to_ahit(timer));

- return count;
+out:
+ up(&hba->host_sem);
+ return ret ? ret : count;
}

static DEVICE_ATTR_RW(rpm_lvl);
@@ -225,12 +245,21 @@ static ssize_t ufs_sysfs_read_desc_param(struct ufs_hba *hba,
if (param_size > 8)
return -EINVAL;

+ down(&hba->host_sem);
+ if (hba->shutting_down) {
+ ret = -EBUSY;
+ goto out;
+ }
+
pm_runtime_get_sync(hba->dev);
ret = ufshcd_read_desc_param(hba, desc_id, desc_index,
param_offset, desc_buf, param_size);
pm_runtime_put_sync(hba->dev);
- if (ret)
- return -EINVAL;
+ if (ret) {
+ ret = -EINVAL;
+ goto out;
+ }
+
switch (param_size) {
case 1:
ret = sprintf(sysfs_buf, "0x%02X\n", *desc_buf);
@@ -249,6 +278,8 @@ static ssize_t ufs_sysfs_read_desc_param(struct ufs_hba *hba,
break;
}

+out:
+ up(&hba->host_sem);
return ret;
}

@@ -591,9 +622,16 @@ static ssize_t _name##_show(struct device *dev, \
int desc_len = QUERY_DESC_MAX_SIZE; \
u8 *desc_buf; \
\
+ down(&hba->host_sem); \
+ if (hba->shutting_down) { \
+ up(&hba->host_sem); \
+ return -EBUSY; \
+ } \
desc_buf = kzalloc(QUERY_DESC_MAX_SIZE, GFP_ATOMIC); \
- if (!desc_buf) \
- return -ENOMEM; \
+ if (!desc_buf) { \
+ up(&hba->host_sem); \
+ return -ENOMEM; \
+ } \
pm_runtime_get_sync(hba->dev); \
ret = ufshcd_query_descriptor_retry(hba, \
UPIU_QUERY_OPCODE_READ_DESC, QUERY_DESC_IDN_DEVICE, \
@@ -613,6 +651,7 @@ static ssize_t _name##_show(struct device *dev, \
out: \
pm_runtime_put_sync(hba->dev); \
kfree(desc_buf); \
+ up(&hba->host_sem); \
return ret; \
} \
static DEVICE_ATTR_RO(_name)
@@ -651,15 +690,26 @@ static ssize_t _name##_show(struct device *dev, \
u8 index = 0; \
int ret; \
struct ufs_hba *hba = dev_get_drvdata(dev); \
+ \
+ down(&hba->host_sem); \
+ if (hba->shutting_down) { \
+ up(&hba->host_sem); \
+ return -EBUSY; \
+ } \
if (ufshcd_is_wb_flags(QUERY_FLAG_IDN##_uname)) \
index = ufshcd_wb_get_query_index(hba); \
pm_runtime_get_sync(hba->dev); \
ret = ufshcd_query_flag(hba, UPIU_QUERY_OPCODE_READ_FLAG, \
QUERY_FLAG_IDN##_uname, index, &flag); \
pm_runtime_put_sync(hba->dev); \
- if (ret) \
- return -EINVAL; \
- return sprintf(buf, "%s\n", flag ? "true" : "false"); \
+ if (ret) { \
+ ret = -EINVAL; \
+ goto out; \
+ } \
+ ret = sprintf(buf, "%s\n", flag ? "true" : "false"); \
+out: \
+ up(&hba->host_sem); \
+ return ret; \
} \
static DEVICE_ATTR_RO(_name)

@@ -709,15 +759,26 @@ static ssize_t _name##_show(struct device *dev, \
u32 value; \
int ret; \
u8 index = 0; \
+ \
+ down(&hba->host_sem); \
+ if (hba->shutting_down) { \
+ up(&hba->host_sem); \
+ return -EBUSY; \
+ } \
if (ufshcd_is_wb_attrs(QUERY_ATTR_IDN##_uname)) \
index = ufshcd_wb_get_query_index(hba); \
pm_runtime_get_sync(hba->dev); \
ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR, \
QUERY_ATTR_IDN##_uname, index, 0, &value); \
pm_runtime_put_sync(hba->dev); \
- if (ret) \
- return -EINVAL; \
- return sprintf(buf, "0x%08X\n", value); \
+ if (ret) { \
+ ret = -EINVAL; \
+ goto out; \
+ } \
+ ret = sprintf(buf, "0x%08X\n", value); \
+out: \
+ up(&hba->host_sem); \
+ return ret; \
} \
static DEVICE_ATTR_RO(_name)

@@ -850,13 +911,26 @@ static ssize_t dyn_cap_needed_attribute_show(struct device *dev,
u8 lun = ufshcd_scsi_to_upiu_lun(sdev->lun);
int ret;

+ down(&hba->host_sem);
+ if (hba->shutting_down) {
+ ret = -EBUSY;
+ goto out;
+ }
+
pm_runtime_get_sync(hba->dev);
ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
QUERY_ATTR_IDN_DYN_CAP_NEEDED, lun, 0, &value);
pm_runtime_put_sync(hba->dev);
- if (ret)
- return -EINVAL;
- return sprintf(buf, "0x%08X\n", value);
+ if (ret) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = sprintf(buf, "0x%08X\n", value);
+
+out:
+ up(&hba->host_sem);
+ return ret;
}
static DEVICE_ATTR_RO(dyn_cap_needed_attribute);

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 34e2541..b035bd0 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1522,11 +1522,17 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
{
struct ufs_hba *hba = dev_get_drvdata(dev);
u32 value;
- int err;
+ int err = 0;

if (kstrtou32(buf, 0, &value))
return -EINVAL;

+ down(&hba->host_sem);
+ if (hba->shutting_down) {
+ err = -EBUSY;
+ goto out;
+ }
+
value = !!value;
if (value == hba->clk_scaling.is_allowed)
goto out;
@@ -1552,7 +1558,8 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
ufshcd_release(hba);
pm_runtime_put_sync(hba->dev);
out:
- return count;
+ up(&hba->host_sem);
+ return err ? err : count;
}

static void ufshcd_clkscaling_init_sysfs(struct ufs_hba *hba)
@@ -5720,9 +5727,10 @@ static void ufshcd_err_handling_unprepare(struct ufs_hba *hba)

static inline bool ufshcd_err_handling_should_stop(struct ufs_hba *hba)
{
- return (!hba->is_powered || hba->ufshcd_state == UFSHCD_STATE_ERROR ||
+ return (!hba->is_powered || hba->shutting_down ||
+ hba->ufshcd_state == UFSHCD_STATE_ERROR ||
(!(hba->saved_err || hba->saved_uic_err || hba->force_reset ||
- ufshcd_is_link_broken(hba))));
+ ufshcd_is_link_broken(hba))));
}

#ifdef CONFIG_PM
@@ -5792,13 +5800,13 @@ static void ufshcd_err_handler(struct work_struct *work)

hba = container_of(work, struct ufs_hba, eh_work);

- down(&hba->eh_sem);
+ down(&hba->host_sem);
spin_lock_irqsave(hba->host->host_lock, flags);
if (ufshcd_err_handling_should_stop(hba)) {
if (hba->ufshcd_state != UFSHCD_STATE_ERROR)
hba->ufshcd_state = UFSHCD_STATE_OPERATIONAL;
spin_unlock_irqrestore(hba->host->host_lock, flags);
- up(&hba->eh_sem);
+ up(&hba->host_sem);
return;
}
ufshcd_set_eh_in_progress(hba);
@@ -5967,7 +5975,7 @@ static void ufshcd_err_handler(struct work_struct *work)
spin_unlock_irqrestore(hba->host->host_lock, flags);
ufshcd_scsi_unblock_requests(hba);
ufshcd_err_handling_unprepare(hba);
- up(&hba->eh_sem);
+ up(&hba->host_sem);
}

/**
@@ -7869,10 +7877,10 @@ static void ufshcd_async_scan(void *data, async_cookie_t cookie)
struct ufs_hba *hba = (struct ufs_hba *)data;
int ret;

- down(&hba->eh_sem);
+ down(&hba->host_sem);
/* Initialize hba, detect and initialize UFS device */
ret = ufshcd_probe_hba(hba, true);
- up(&hba->eh_sem);
+ up(&hba->host_sem);
if (ret)
goto out;

@@ -8899,7 +8907,7 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
if (!hba)
return 0;

- down(&hba->eh_sem);
+ down(&hba->host_sem);
if (!hba->is_powered)
return 0;

@@ -8931,7 +8939,7 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
if (!ret)
hba->is_sys_suspended = true;
else
- up(&hba->eh_sem);
+ up(&hba->host_sem);
return ret;
}
EXPORT_SYMBOL(ufshcd_system_suspend);
@@ -8965,7 +8973,7 @@ int ufshcd_system_resume(struct ufs_hba *hba)
hba->curr_dev_pwr_mode, hba->uic_link_state);
if (!ret)
hba->is_sys_suspended = false;
- up(&hba->eh_sem);
+ up(&hba->host_sem);
return ret;
}
EXPORT_SYMBOL(ufshcd_system_resume);
@@ -9057,7 +9065,10 @@ int ufshcd_shutdown(struct ufs_hba *hba)
{
int ret = 0;

- down(&hba->eh_sem);
+ down(&hba->host_sem);
+ hba->shutting_down = true;
+ up(&hba->host_sem);
+
if (!hba->is_powered)
goto out;

@@ -9075,7 +9086,6 @@ int ufshcd_shutdown(struct ufs_hba *hba)
if (ret)
dev_err(hba->dev, "%s failed, err %d\n", __func__, ret);
hba->is_powered = false;
- up(&hba->eh_sem);
/* allow force shutdown even in case of errors */
return 0;
}
@@ -9270,7 +9280,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
INIT_WORK(&hba->eh_work, ufshcd_err_handler);
INIT_WORK(&hba->eeh_work, ufshcd_exception_event_handler);

- sema_init(&hba->eh_sem, 1);
+ sema_init(&hba->host_sem, 1);

/* Initialize UIC command mutex */
mutex_init(&hba->uic_cmd_mutex);
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 9bb5f0e..af33c82 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -655,6 +655,8 @@ struct ufs_hba_variant_params {
* @intr_mask: Interrupt Mask Bits
* @ee_ctrl_mask: Exception event control mask
* @is_powered: flag to check if HBA is powered
+ * @shutting_down: flag to check if shutdown has been invoked
+ * @host_sem: semaphore used to serialize concurrent contexts
* @eh_wq: Workqueue that eh_work works on
* @eh_work: Worker to handle UFS errors that require s/w attention
* @eeh_work: Worker to handle exception events
@@ -751,7 +753,8 @@ struct ufs_hba {
u32 intr_mask;
u16 ee_ctrl_mask;
bool is_powered;
- struct semaphore eh_sem;
+ bool shutting_down;
+ struct semaphore host_sem;

/* Work Queues */
struct workqueue_struct *eh_wq;
--
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Next message: Can Guo: "Re: [PATCH v8 1/3] scsi: ufs: Protect some contexts from unexpected clock scaling"
Previous message: Joseph Qi: "Re: [PATCH] ocfs2: Remove redundant conditional before iput"
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