This is a note to let you know that I've just added the patch titled
usb: gadget: f_fs: Fix use-after-free in ffs_free_inst
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-gadget-f_fs-fix-use-after-free-in-ffs_free_inst.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From cdafb6d8b8da7fde266f79b3287ac221aa841879 Mon Sep 17 00:00:00 2001
From: Andrew Gabbasov <andrew_gabbasov@xxxxxxxxxx>
Date: Wed, 8 Nov 2017 10:13:15 -0700
Subject: usb: gadget: f_fs: Fix use-after-free in ffs_free_inst
From: Andrew Gabbasov <andrew_gabbasov@xxxxxxxxxx>
commit cdafb6d8b8da7fde266f79b3287ac221aa841879 upstream.
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")
Signed-off-by: Andrew Gabbasov <andrew_gabbasov@xxxxxxxxxx>
Acked-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/gadget/function/f_fs.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -3698,6 +3698,7 @@ static void ffs_closed(struct ffs_data *
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)
Patches currently in stable-queue which might be from andrew_gabbasov@xxxxxxxxxx are
queue-4.9/usb-gadget-f_fs-fix-use-after-free-in-ffs_free_inst.patch