From: Arnd Bergmann <arnd@kernel.org>
To: Russell King <linux@armlinux.org.uk>,
Arnd Bergmann <arnd@arndb.de>,
Kyungmin Park <kyungmin.park@samsung.com>,
Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: [PATCH] ARM: dma-mapping: fix out of bounds access in CMA
Date: Tue, 23 Mar 2021 14:14:13 +0100 [thread overview]
Message-ID: <20210323131423.2581218-1-arnd@kernel.org> (raw)
From: Arnd Bergmann <arnd@arndb.de>
Dereferencing a zero-length array is always a bug, and we get a warning
with 'make W=1' here:
arch/arm/mm/dma-mapping.c: In function 'dma_contiguous_early_fixup':
arch/arm/mm/dma-mapping.c:395:15: error: array subscript <unknown> is outside array bounds of 'struct dma_contig_early_reserve[0]' [-Werror=array-bounds]
395 | dma_mmu_remap[dma_mmu_remap_num].base = base;
| ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
arch/arm/mm/dma-mapping.c:389:40: note: while referencing 'dma_mmu_remap'
389 | static struct dma_contig_early_reserve dma_mmu_remap[MAX_CMA_AREAS] __initdata;
| ^~~~~~~~~~~~~
arch/arm/mm/dma-mapping.c:396:15: error: array subscript <unknown> is outside array bounds of 'struct dma_contig_early_reserve[0]' [-Werror=array-bounds]
Add a runtime check to prevent this from happening, while also
avoiding the compile-time warning.
Fixes: c79095092834 ("ARM: integrate CMA with DMA-mapping subsystem")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
arch/arm/mm/dma-mapping.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index c4b8df2ad328..af29344fb150 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -392,6 +392,11 @@ static int dma_mmu_remap_num __initdata;
void __init dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)
{
+ if (!MAX_CMA_AREAS || dma_mmu_remap_num >= MAX_CMA_AREAS) {
+ WARN_ONCE(1, "number of CMA areas\n");
+ return;
+ }
+
dma_mmu_remap[dma_mmu_remap_num].base = base;
dma_mmu_remap[dma_mmu_remap_num].size = size;
dma_mmu_remap_num++;
@@ -400,6 +405,10 @@ void __init dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)
void __init dma_contiguous_remap(void)
{
int i;
+
+ if (!MAX_CMA_AREAS)
+ return;
+
for (i = 0; i < dma_mmu_remap_num; i++) {
phys_addr_t start = dma_mmu_remap[i].base;
phys_addr_t end = start + dma_mmu_remap[i].size;
--
2.29.2
next reply other threads:[~2021-03-23 13:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 13:14 Arnd Bergmann [this message]
2021-03-23 13:28 ` [PATCH] ARM: dma-mapping: fix out of bounds access in CMA Russell King - ARM Linux admin
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