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@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
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);
}
--
2.17.1
