lkml.org 
[lkml]   [2022]   [Apr]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] drivers: nfc: nfcmrvl: reorder destructive operations in nfcmrvl_nci_unregister_dev to avoid bugs
Date
There are destructive operations such as nfcmrvl_fw_dnld_abort and
gpio_free in nfcmrvl_nci_unregister_dev. The resources such as firmware,
gpio and so on could be destructed while the upper layer functions such as
nfcmrvl_fw_dnld_start and nfcmrvl_nci_recv_frame is executing, which leads
to double-free, use-after-free and null-ptr-deref bugs.

There are three situations that could lead to double-free bugs.

The first situation 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 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 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, gpio or
set null to the members of priv->fw_dnld in nfcmrvl_nci_unregister_dev,
then, we dereference firmware, gpio or the members of priv->fw_dnld in
nfcmrvl_fw_dnld_start, the UAF or NPD bugs will happen.

This patch reorders destructive operations 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.
This was mentioned in commit 3e3b5dfcd16a ("NFC: reorder the logic in
nfc_{un,}register_device").

Fixes: 3194c6870158 ("NFC: nfcmrvl: add firmware download support")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reviewed-by: Lin Ma <linma@zju.edu.cn>
---
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
\
 
 \ /
  Last update: 2022-04-25 05:11    [W:0.041 / U:0.260 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site