linux-kernel - [PATCH pstore fix v1] pstore: fix use after free

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <1562331960-26198-1-git-send-email-nmanthey@amazon.de>
Date:   Fri, 5 Jul 2019 15:06:00 +0200
From:   Norbert Manthey <nmanthey@...zon.de>
To:     Norbert Manthey <nmanthey@...zon.de>,
        <linux-kernel@...r.kernel.org>
CC:     David Woodhouse <dwmw@...zon.co.uk>,
        Kees Cook <keescook@...omium.org>,
        Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        "Tony Luck" <tony.luck@...el.com>
Subject: [PATCH pstore fix v1] pstore: fix use after free

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@...zon.de>

---
 fs/pstore/inode.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -333,7 +333,6 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 	private = kzalloc(sizeof(*private), GFP_KERNEL);
 	if (!private)
 		goto fail_alloc;
-	private->record = record;

 	switch (record->type) {
 	case PSTORE_TYPE_DMESG:
@@ -387,6 +386,8 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 	if (!dentry)
 		goto fail_private;

+	private->record = record;
+
 	inode->i_size = private->total_size = size;

 	inode->i_private = private;
-- 
2.7.4

Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879