linux-kernel - [PATCH net] atm: fore200e: fix use-after-free in tasklets during device removal

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <20260205030317.39190-1-duoming@zju.edu.cn>
Date: Thu,  5 Feb 2026 11:03:17 +0800
From: Duoming Zhou <duoming@....edu.cn>
To: netdev@...r.kernel.org
Cc: linux-atm-general@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org,
	3chas3@...il.com,
	Duoming Zhou <duoming@....edu.cn>
Subject: [PATCH net] atm: fore200e: fix use-after-free in tasklets during device removal

When the PCA-200E or SBA-200E adapters is being detached, the fore200e
is deallocated. However, the tx_tasklet or rx_tasklet may still be running
or pending, leading to use-after-free bug when the already freed fore200e
is accessed again in fore200e_tx_tasklet() or fore200e_rx_tasklet().

One of the race conditions can occur as follows:

CPU 0 (cleanup)           | CPU 1 (tasklet)
fore200e_pca_remove_one() | fore200e_interrupt()
  fore200e_shutdown()     |   tasklet_schedule()
    kfree(fore200e)       | fore200e_tx_tasklet()
                          |   fore200e-> // UAF

Fix this by ensuring tx_tasklet or rx_tasklet is properly canceled before
the fore200e is released. Add tasklet_kill() in fore200e_shutdown() to
synchronize with any pending or running tasklets.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Duoming Zhou <duoming@....edu.cn>
---
 drivers/atm/fore200e.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/atm/fore200e.c b/drivers/atm/fore200e.c
index f62e3857144..7470daf9469 100644
--- a/drivers/atm/fore200e.c
+++ b/drivers/atm/fore200e.c
@@ -358,7 +358,12 @@ fore200e_shutdown(struct fore200e* fore200e)
     printk(FORE200E "removing device %s at 0x%lx, IRQ %s\n",
 	   fore200e->name, fore200e->phys_base, 
 	   fore200e_irq_itoa(fore200e->irq));
-    
+
+#ifdef FORE200E_USE_TASKLET
+	tasklet_kill(&fore200e->tx_tasklet);
+	tasklet_kill(&fore200e->rx_tasklet);
+#endif
+
     if (fore200e->state > FORE200E_STATE_RESET) {
 	/* first, reset the board to prevent further interrupts or data transfers */
 	fore200e_reset(fore200e, 0);
-- 
2.34.1