Re: [PATCH 120/190] Revert "tty: atmel_serial: fix a potential NULL pointer dereference"

From: Jiri Slaby
Date: Thu Apr 22 2021 - 01:18:24 EST


On 21. 04. 21, 14:59, Greg Kroah-Hartman wrote:
This reverts commit c85be041065c0be8bc48eda4c45e0319caf1d0e5.

Commits from @umn.edu addresses have been found to be submitted in "bad
faith" to try to test the kernel community's ability to review "known
malicious" changes. The result of these submissions can be found in a
paper published at the 42nd IEEE Symposium on Security and Privacy
entitled, "Open Source Insecurity: Stealthily Introducing
Vulnerabilities via Hypocrite Commits" written by Qiushi Wu (University
of Minnesota) and Kangjie Lu (University of Minnesota).

Because of this, all submissions from this group must be reverted from
the kernel tree and will need to be re-reviewed again to determine if
they actually are a valid fix. Until that work is complete, remove this
change to ensure that no problems are being introduced into the
codebase.

Cc: Kangjie Lu <kjlu@xxxxxxx>
Cc: Richard Genoud <richard.genoud@xxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/atmel_serial.c | 4 ----
1 file changed, 4 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index a24e5c2b30bc..9786d8e5f04f 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1256,10 +1256,6 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
sg_dma_len(&atmel_port->sg_rx)/2,
DMA_DEV_TO_MEM,
DMA_PREP_INTERRUPT);
- if (!desc) {
- dev_err(port->dev, "Preparing DMA cyclic failed\n");
- goto chan_err;
- }

I cannot find anything malicious in the original fix:
* port->dev is valid for dev_err
* dmaengine_prep_dma_cyclic returns NULL in case of error
* chan_err invokes atmel_release_rx_dma which undoes the previous initialization code.

Hence a NACK from me for the revert.

desc->callback = atmel_complete_rx_dma;
desc->callback_param = port;
atmel_port->desc_rx = desc;



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