From 09afa9e360259e8c797c5778df73c9bb645a0725 Mon Sep 17 00:00:00 2001
From: Norbert Manthey <nmanthey@amazon.de>
Date: Fri, 5 Jul 2019 15:06:00 +0200
Subject: [PATCH] pstore: Fix double-free in pstore_mkfile() failure path
commit 4c6d80e1144bdf48cae6b602ae30d41f3e5c76a9 upstream.
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 <nmanthey@amazon.de>
Link: https://lore.kernel.org/r/1562331960-26198-1-git-send-email-nmanthey@amazon.de
Fixes: 83f70f0769ddd ("pstore: Do not duplicate record metadata")
Fixes: 1dfff7dd67d1a ("pstore: Pass record contents instead of copying")
Cc: stable@vger.kernel.org
[kees: also move "private" allocation location, rename inode cleanup label]
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/pstore/inode.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index c60ee46f3e393..fc91f7263f796 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -330,22 +330,21 @@ 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)
@@ -361,7 +360,7 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
fail_private:
free_pstore_private(private);
-fail_alloc:
+fail_inode:
iput(inode);
fail: