From: Andrew Gabbasov <andrew_gabbasov@mentor.com>
To: Felipe Balbi <balbi@kernel.org>, <linux-usb@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: [PATCH] usb: gadget: f_fs: Fix use-after-free in ffs_free_inst
Date: Wed, 8 Nov 2017 10:13:15 -0700 [thread overview]
Message-ID: <1510161195-24838-1-git-send-email-andrew_gabbasov@mentor.com> (raw)
KASAN enabled configuration reports an error
BUG: KASAN: use-after-free in ffs_free_inst+... [usb_f_fs] at addr ...
Write of size 8 by task ...
This is observed after "ffs-test" is run and interrupted. If after that
functionfs is unmounted and g_ffs module is unloaded, that use-after-free
occurs during g_ffs module removal.
Although the report indicates ffs_free_inst() function, the actual
use-after-free condition occurs in _ffs_free_dev() function, which
is probably inlined into ffs_free_inst().
This happens due to keeping the ffs_data reference in device structure
during functionfs unmounting, while ffs_data itself is freed as no longer
needed. The fix is to clear that reference in ffs_closed() function,
which is a counterpart of ffs_ready(), where the reference is stored.
Fixes: 3262ad824307 ("usb: gadget: f_fs: Stop ffs_closed NULL pointer dereference")
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
---
drivers/usb/gadget/function/f_fs.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 8b34258..ef8f7d6 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -3677,6 +3677,7 @@ static void ffs_closed(struct ffs_data *ffs)
goto done;
ffs_obj->desc_ready = false;
+ ffs_obj->ffs_data = NULL;
if (test_and_clear_bit(FFS_FL_CALL_CLOSED_CALLBACK, &ffs->flags) &&
ffs_obj->ffs_closed_callback)
--
2.1.0
next reply other threads:[~2017-11-08 17:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-08 17:13 Andrew Gabbasov [this message]
2017-11-09 12:01 ` [PATCH] usb: gadget: f_fs: Fix use-after-free in ffs_free_inst Greg KH
2017-11-09 12:03 ` Felipe Balbi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1510161195-24838-1-git-send-email-andrew_gabbasov@mentor.com \
--to=andrew_gabbasov@mentor.com \
--cc=balbi@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).