From: Sonia Sharma <sharmaso@whamcloud.com>
Date: Mon, 1 Apr 2019 12:40:27 +0000 (-0700)
Subject: LU-11986 lnet: Avoid lnet debugfs read/write if ctl_table does not exist
X-Git-Tag: 2.12.53~34
X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=commitdiff_plain;h=013dafd857d1c8f045a704c865f99a53b777c5e3

LU-11986 lnet: Avoid lnet debugfs read/write if ctl_table does not exist

Running command "lctl get param -n stats" after lnet
is taken down leads to kernel panic because it
tries to read from the file which doesnt exist
anymore.

In lnet_debugfs_read() and lnet_debugfs_write(),
check if struct ctl_table is valid before trying
to read/write to it.

Change-Id: I2450d2f89c2e8a7db793680a4df581282ee46a16
Signed-off-by: Sonia Sharma <sharmaso@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/34622
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
---

diff --git a/libcfs/libcfs/module.c b/libcfs/libcfs/module.c
index 99b6f79..3a696e9 100644
--- a/libcfs/libcfs/module.c
+++ b/libcfs/libcfs/module.c
@@ -491,11 +491,13 @@ static ssize_t lnet_debugfs_read(struct file *filp, char __user *buf,
 				 size_t count, loff_t *ppos)
 {
 	struct ctl_table *table = filp->private_data;
-	ssize_t rc;
+	ssize_t rc = -EINVAL;
 
-	rc = table->proc_handler(table, 0, buf, &count, ppos);
-	if (!rc)
-		rc = count;
+	if (table) {
+		rc = table->proc_handler(table, 0, buf, &count, ppos);
+		if (!rc)
+			rc = count;
+	}
 
 	return rc;
 }
@@ -504,11 +506,14 @@ static ssize_t lnet_debugfs_write(struct file *filp, const char __user *buf,
 				  size_t count, loff_t *ppos)
 {
 	struct ctl_table *table = filp->private_data;
-	ssize_t rc;
+	ssize_t rc = -EINVAL;
 
-	rc = table->proc_handler(table, 1, (void __user *)buf, &count, ppos);
-	if (!rc)
-		rc = count;
+	if (table) {
+		rc = table->proc_handler(table, 1, (void __user *)buf, &count,
+					 ppos);
+		if (!rc)
+			rc = count;
+	}
 
 	return rc;
 }