linux-kernel - [PATCH] media: cx25821: Fix a bug when reallocating some dma memory

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Message-Id: <20210116212146.555745-1-christophe.jaillet@wanadoo.fr>
Date:   Sat, 16 Jan 2021 22:21:46 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     mchehab@...nel.org, hverkuil-cisco@...all.nl,
        vaibhavgupta40@...il.com, tglx@...utronix.de
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] media: cx25821: Fix a bug when reallocating some dma memory

This function looks like a realloc.

However, if 'risc->cpu != NULL', the memory will be freed, but never
reallocated with the bigger 'size'.
Explicitly set 'risc->cpu' to NULL, so that the reallocation is
correctly performed a few lines below.

Fixes: 5ede94c70553 ("[media] cx25821: remove bogus btcx_risc dependency)
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
Completly speculative and untested.
---
 drivers/media/pci/cx25821/cx25821-core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/pci/cx25821/cx25821-core.c b/drivers/media/pci/cx25821/cx25821-core.c
index 6f8ffab8840f..22e47dd74df4 100644
--- a/drivers/media/pci/cx25821/cx25821-core.c
+++ b/drivers/media/pci/cx25821/cx25821-core.c
@@ -976,8 +976,10 @@ int cx25821_riscmem_alloc(struct pci_dev *pci,
 	__le32 *cpu;
 	dma_addr_t dma = 0;
 
-	if (NULL != risc->cpu && risc->size < size)
+	if (NULL != risc->cpu && risc->size < size) {
 		pci_free_consistent(pci, risc->size, risc->cpu, risc->dma);
+		risc->cpu = NULL;
+	}
 	if (NULL == risc->cpu) {
 		cpu = pci_zalloc_consistent(pci, size, &dma);
 		if (NULL == cpu)
-- 
2.27.0