Messages in this thread Patch in this message | | | From | Andrew Gabbasov <> | Subject | [PATCH] usb: gadget: f_fs: Fix use-after-free in ffs_free_inst | Date | Wed, 8 Nov 2017 10:13:15 -0700 |
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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
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