linux-hardening - [PATCH 1/2] dmaengine: pxa_dma: Remove an erroneous BUG_ON() in pxad_free

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Date: Sat,  7 Oct 2023 13:13:09 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: keescook@...omium.org,
	gustavoars@...nel.org,
	Daniel Mack <daniel@...que.org>,
	Haojian Zhuang <haojian.zhuang@...il.com>,
	Robert Jarzmik <robert.jarzmik@...e.fr>,
	Vinod Koul <vkoul@...nel.org>
Cc: linux-hardening@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	linux-arm-kernel@...ts.infradead.org,
	dmaengine@...r.kernel.org
Subject: [PATCH 1/2] dmaengine: pxa_dma: Remove an erroneous BUG_ON() in pxad_free_desc()

If pxad_alloc_desc() fails on the first dma_pool_alloc() call, then
sw_desc->nb_desc is zero.
In such a case pxad_free_desc() is called and it will BUG_ON().

Remove this erroneous BUG_ON().

It is also useless, because if "sw_desc->nb_desc == 0", then, on the first
iteration of the for loop, i is -1 and the loop will not be executed.
(both i and sw_desc->nb_desc are 'int')

Fixes: a57e16cf0333 ("dmaengine: pxa: add pxa dmaengine driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
 drivers/dma/pxa_dma.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
index 3c574dc0613b..94cef2905940 100644
--- a/drivers/dma/pxa_dma.c
+++ b/drivers/dma/pxa_dma.c
@@ -722,7 +722,6 @@ static void pxad_free_desc(struct virt_dma_desc *vd)
 	dma_addr_t dma;
 	struct pxad_desc_sw *sw_desc = to_pxad_sw_desc(vd);
 
-	BUG_ON(sw_desc->nb_desc == 0);
 	for (i = sw_desc->nb_desc - 1; i >= 0; i--) {
 		if (i > 0)
 			dma = sw_desc->hw_desc[i - 1]->ddadr;
-- 
2.34.1