linux-kernel - [PATCH] initramfs: Fix a missing-check bug in init/initramfs.c

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Date:   Wed, 22 May 2019 09:04:55 +0800
From:   Gen Zhang <blackgod016574@...il.com>
To:     lizhijian@...fujitsu.com
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] initramfs: Fix a missing-check bug in init/initramfs.c

In dir_add(), de and de->name are allocated by kmalloc() and kstrdup().
And de->name is dereferenced in the following codes. However, memory
allocation functions such as kmalloc() and kstrdup() may fail.
Dereferencing this de->name null pointer may cause the kernel go wrong.
Thus we should check this allocation.
Further, if kstrdup() returns NULL, we should free de and panic().

Signed-off-by: Gen Zhang <blackgod016574@...il.com>

---
diff --git a/init/initramfs.c b/init/initramfs.c
index 178130f..dc8063f 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -125,6 +125,10 @@ static void __init dir_add(const char *name, time64_t mtime)
 		panic("can't allocate dir_entry buffer");
 	INIT_LIST_HEAD(&de->list);
 	de->name = kstrdup(name, GFP_KERNEL);
+	if (!de->name) {
+		kfree(de);
+		panic("can't allocate dir_entry name buffer");
+	}
 	de->mtime = mtime;
 	list_add(&de->list, &dir_list);
 }