From 5000fe6c27827a61d8250a7e4a1d26c3298ef4f6 Mon Sep 17 00:00:00 2001

From: Zheng Wang <zyytlz.wz@163.com>

Date: Mon, 13 Mar 2023 00:08:37 +0800

Subject: [PATCH] nfc: st-nci: Fix use after free bug in ndlc_remove due to race condition

Git-commit: 5000fe6c27827a61d8250a7e4a1d26c3298ef4f6

Patch-mainline: v6.3-rc3

References: git-fixes bsc#1210337 CVE-2023-1990

This bug influences both st_nci_i2c_remove and st_nci_spi_remove.

Take st_nci_i2c_remove as an example.

In st_nci_i2c_probe, it called ndlc_probe and bound &ndlc->sm_work

with llt_ndlc_sm_work.

When it calls ndlc_recv or timeout handler, it will finally call

schedule_work to start the work.

When we call st_nci_i2c_remove to remove the driver, there

may be a sequence as follows:

Fix it by finishing the work before cleanup in ndlc_remove

CPU0                  CPU1

                    |llt_ndlc_sm_work

st_nci_i2c_remove   |

  ndlc_remove       |

     st_nci_remove  |

     nci_free_device|

     kfree(ndev)    |

//free ndlc->ndev   |

                    |llt_ndlc_rcv_queue

                    |nci_recv_frame

                    |//use ndlc->ndev

Fixes: 35630df68d60 ("NFC: st21nfcb: Add driver for STMicroelectronics ST21NFCB NFC chip")

Signed-off-by: Zheng Wang <zyytlz.wz@163.com>

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Link: https://lore.kernel.org/r/20230312160837.2040857-1-zyytlz.wz@163.com

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Acked-by: Takashi Iwai <tiwai@suse.de>

Acked-by: Chester Lin <clin@suse.com>

---

 drivers/nfc/st-nci/ndlc.c | 6 ++++--

 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/nfc/st-nci/ndlc.c b/drivers/nfc/st-nci/ndlc.c

index 755460a73c0d..d2aa9f766738 100644

--- a/drivers/nfc/st-nci/ndlc.c

+++ b/drivers/nfc/st-nci/ndlc.c

@@ -282,13 +282,15 @@ EXPORT_SYMBOL(ndlc_probe);

 void ndlc_remove(struct llt_ndlc *ndlc)

 {

-	st_nci_remove(ndlc->ndev);

-

 	/* cancel timers */

 	del_timer_sync(&ndlc->t1_timer);

 	del_timer_sync(&ndlc->t2_timer);

 	ndlc->t2_active = false;

 	ndlc->t1_active = false;

+	/* cancel work */

+	cancel_work_sync(&ndlc->sm_work);

+

+	st_nci_remove(ndlc->ndev);

 	skb_queue_purge(&ndlc->rcv_q);

 	skb_queue_purge(&ndlc->send_q);

-- 

2.35.3