The fw_dnld_over() is a reentrant function in nfcmrvl driver, it could be called by nfcmrvl_fw_dnld_start(), nfcmrvl_nci_recv_frame() and nfcmrvl_nci_unregister_dev() without synchronization. As a result, the firmware struct could be deallocated more than once, which leads to double-free or invalid-free bugs.

The first situation that causes bug is shown below:

(Thread 1) | (Thread 2) nfcmrvl_fw_dnld_start | ... | nfcmrvl_nci_unregister_dev release_firmware() | nfcmrvl_fw_dnld_abort kfree(fw) //(1) | fw_dnld_over | release_firmware ... | kfree(fw) //(2) | ...

The second situation that causes bug is shown below:

(Thread 1) | (Thread 2) nfcmrvl_fw_dnld_start | ... | mod_timer | (wait a time) | fw_dnld_timeout | nfcmrvl_nci_unregister_dev fw_dnld_over | nfcmrvl_fw_dnld_abort release_firmware | fw_dnld_over kfree(fw) //(1) | release_firmware ... | kfree(fw) //(2)

The third situation that causes bug is shown below:

(Thread 1) | (Thread 2) nfcmrvl_nci_recv_frame | if(..->fw_download_in_progress)| nfcmrvl_fw_dnld_recv_frame | queue_work | | fw_dnld_rx_work | nfcmrvl_nci_unregister_dev fw_dnld_over | nfcmrvl_fw_dnld_abort release_firmware | fw_dnld_over kfree(fw) //(1) | release_firmware | kfree(fw) //(2)

The firmware struct is deallocated in position (1) and deallocated in position (2) again.

The crash trace triggered by POC is like below:

[ 122.640457] BUG: KASAN: double-free or invalid-free in fw_dnld_over+0x28/0xf0 [ 122.640457] Call Trace: [ 122.640457] <TASK> [ 122.640457] kfree+0xb0/0x330 [ 122.640457] fw_dnld_over+0x28/0xf0 [ 122.640457] nfcmrvl_nci_unregister_dev+0x61/0x70 [ 122.640457] nci_uart_tty_close+0x87/0xd0 [ 122.640457] tty_ldisc_kill+0x3e/0x80 [ 122.640457] tty_ldisc_hangup+0x1b2/0x2c0 [ 122.640457] __tty_hangup.part.0+0x316/0x520 [ 122.640457] tty_release+0x200/0x670 [ 122.640457] __fput+0x110/0x410 [ 122.640457] task_work_run+0x86/0xd0 [ 122.640457] exit_to_user_mode_prepare+0x1aa/0x1b0 [ 122.640457] syscall_exit_to_user_mode+0x19/0x50 [ 122.640457] do_syscall_64+0x48/0x90 [ 122.640457] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 122.640457] RIP: 0033:0x7f68433f6beb

What's more, there are also use-after-free and null-ptr-deref bugs in nfcmrvl_fw_dnld_start(). If we deallocate firmware struct or set null to the members of priv->fw_dnld in fw_dnld_over(), then, we dereference firmware or the members of priv->fw_dnld in nfcmrvl_fw_dnld_start(), the UAF or NPD bugs will happen.

This patch reorders nfcmrvl_fw_dnld_abort() after nci_unregister_device() to avoid the double-free, UAF and NPD bugs, as nci_unregister_device() is well synchronized and won't return if there is a running routine.

Fixes: 3194c6870158 ("NFC: nfcmrvl: add firmware download support") Signed-off-by: Duoming Zhou duoming@zju.edu.cn Cc: stable@vger.kernel.org --- drivers/nfc/nfcmrvl/main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nfc/nfcmrvl/main.c b/drivers/nfc/nfcmrvl/main.c index 2fcf545012b..1a5284de434 100644 --- a/drivers/nfc/nfcmrvl/main.c +++ b/drivers/nfc/nfcmrvl/main.c @@ -183,6 +183,7 @@ void nfcmrvl_nci_unregister_dev(struct nfcmrvl_private *priv) { struct nci_dev *ndev = priv->ndev;

+ nci_unregister_device(ndev); if (priv->ndev->nfc_dev->fw_download_in_progress) nfcmrvl_fw_dnld_abort(priv);

@@ -191,7 +192,6 @@ void nfcmrvl_nci_unregister_dev(struct nfcmrvl_private *priv) if (gpio_is_valid(priv->config.reset_n_io)) gpio_free(priv->config.reset_n_io);

- nci_unregister_device(ndev); nci_free_device(ndev); kfree(priv); }