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FAILED: patch "[PATCH] pstore: Fix double-free in pstore_mkfile() failure path" failed to apply to 4.14-stable tree

PATCH [email protected] 1 participant 1 message Jul 24, 2019

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The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4c6d80e1144bdf48cae6b602ae30d41f3e5c76a9 Mon Sep 17 00:00:00 2001
From: Norbert Manthey <[email protected]>
Date: Fri, 5 Jul 2019 15:06:00 +0200
Subject: [PATCH] pstore: Fix double-free in pstore_mkfile() failure path

The pstore_mkfile() function is passed a pointer to a struct pstore_record. On success it consumes this 'record' pointer and references it from the created inode.

On failure, however, it may or may not free the record. There are even two different code paths which return -ENOMEM -- one of which does and the other doesn't free the record.

Make the behaviour deterministic by never consuming and freeing the record when returning failure, allowing the caller to do the cleanup consistently.

Signed-off-by Norbert Manthey <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Fixes 83f70f0769ddd ("pstore: Do not duplicate record metadata")
Fixes 1dfff7dd67d1a ("pstore: Pass record contents instead of copying")
Cc [email protected]
[kees: also move "private" allocation location, rename inode cleanup label]
Signed-off-by Kees Cook <[email protected]>
fs/pstore/inode.c +6 -7
index 89a80b568a17..7fbe8f058220 100644
@@ -318,22 +318,21 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 		goto fail;
 	inode->i_mode = S_IFREG | 0444;
 	inode->i_fop = &pstore_file_operations;
-	private = kzalloc(sizeof(*private), GFP_KERNEL);
-	if (!private)
-		goto fail_alloc;
-	private->record = record;
-
 	scnprintf(name, sizeof(name), "%s-%s-%llu%s",
 			pstore_type_to_name(record->type),
 			record->psi->name, record->id,
 			record->compressed ? ".enc.z" : "");
 
+	private = kzalloc(sizeof(*private), GFP_KERNEL);
+	if (!private)
+		goto fail_inode;
+
 	dentry = d_alloc_name(root, name);
 	if (!dentry)
 		goto fail_private;
 
+	private->record = record;
 	inode->i_size = private->total_size = size;
-
 	inode->i_private = private;
 
 	if (record->time.tv_sec)

@@ -349,7 +348,7 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 
 fail_private:
 	free_pstore_private(private);
-fail_alloc:
+fail_inode:
 	iput(inode);
 
 fail: