Hello,
On Mon, 25 Apr 2022 09:59:32 +0200 Krzysztof wrote:
> > 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.
>
> You need to correct the subject prefix because it does not describe the
> subsystem (git log oneline --).
I will change the subject prefix to "nfc: nfcmrvl: uart: ".
> >
> > 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 <[email protected]>
> > Reviewed-by: Lin Ma <[email protected]>
>
> It's the first submission, how this review appeared?
I will remove the review tag.
> On the other hand, you already sent something similar, so is it a v2? I
> am sorry but this is very confusing. Looks like
> https://lore.kernel.org/all/[email protected]/
> but there is no changelog and commit description is different.
I am sorry the above link is just a test, I forget to remove "Cc: [email protected]".
> Please read:
> https://elixir.bootlin.com/linux/v5.18-rc4/source/Documentation/process/submitting-patches.rst
>
I will send "[PATCH net V2] nfc: nfcmrvl: uart: reorder destructive operations in nfcmrvl_nci_unregister_dev to avoid bugs".
Best regards,
Duoming Zhou