+ fail_function-switch-to-memdup_user_nul-helper.patch added to mm-nonmm-unstable branch

+ fail_function-switch-to-memdup_user_nul-helper.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: fail_function: switch to memdup_user_nul() helper
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     fail_function-switch-to-memdup_user_nul-helper.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fail_function-switch-to-memdup_user_nul-helper.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Yang Yingliang <yangyingliang@huawei.com>
Subject: fail_function: switch to memdup_user_nul() helper
Date: Fri, 26 Aug 2022 15:33:35 +0800

Use memdup_user_nul() helper instead of open-coding to simplify the code.

Link: https://lkml.kernel.org/r/20220826073337.2085798-1-yangyingliang@huawei.com
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/fail_function.c |   15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

--- a/kernel/fail_function.c~fail_function-switch-to-memdup_user_nul-helper
+++ a/kernel/fail_function.c
@@ -247,15 +247,11 @@ static ssize_t fei_write(struct file *fi
 	/* cut off if it is too long */
 	if (count > KSYM_NAME_LEN)
 		count = KSYM_NAME_LEN;
-	buf = kmalloc(count + 1, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
-	if (copy_from_user(buf, buffer, count)) {
-		ret = -EFAULT;
-		goto out_free;
-	}
-	buf[count] = '\0';
+
+	buf = memdup_user_nul(buffer, count);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
 	sym = strstrip(buf);
 
 	mutex_lock(&fei_lock);
@@ -308,7 +304,6 @@ static ssize_t fei_write(struct file *fi
 	}
 out:
 	mutex_unlock(&fei_lock);
-out_free:
 	kfree(buf);
 	return ret;
 }
_

Patches currently in -mm which might be from yangyingliang@huawei.com are

nommu-remove-uses-of-vma-linked-list-fix.patch
fail_function-switch-to-memdup_user_nul-helper.patch
fail_function-refctor-code-of-checking-return-value-of-register_kprobe.patch
fail_function-fix-wrong-use-of-fei_attr_remove.patch