Re: [PATCH] memory: mtk-smi: Fix a null dereference for the ostd
From: Krzysztof Kozlowski <hidden>
Date: 2021-10-29 17:35:54
Also in:
linux-iommu, linux-mediatek, lkml
On 28/10/2021 07:50, Yong Wu wrote:
We add the ostd setting for mt8195. It introduces a abort for the previous SoC which doesn't have ostd setting. This is the log: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000080 ... pc : mtk_smi_larb_config_port_gen2_general+0x64/0x130 lr : mtk_smi_larb_resume+0x54/0x98 ... Call trace: mtk_smi_larb_config_port_gen2_general+0x64/0x130 pm_generic_runtime_resume+0x2c/0x48 __genpd_runtime_resume+0x30/0xa8 genpd_runtime_resume+0x94/0x2c8 __rpm_callback+0x44/0x150 rpm_callback+0x6c/0x78 rpm_resume+0x310/0x558 __pm_runtime_resume+0x3c/0x88 In the code: larbostd = larb->larb_gen->ostd[larb->larbid], if "larb->larb_gen->ostd" is null, the "larbostd" is the offset, it is also a valid value, thus, use the larb->larb_gen->ostd as the condition inside the "for" loop.
You need to write more clearly, what you are fixing here.
quoted hunk ↗ jump to hunk
Signed-off-by: Yong Wu <yong.wu@mediatek.com> --- Hi Krzysztof, Could you help review and conside this as a fix for the mt8195 patchset? The mt8195 patchset are not in mainline, thus, I don't know its sha-id, and don't add Fixes tag. Thanks --- drivers/memory/mtk-smi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/memory/mtk-smi.c b/drivers/memory/mtk-smi.c index b883dcc0bbfa..0262a59a2d6e 100644 --- a/drivers/memory/mtk-smi.c +++ b/drivers/memory/mtk-smi.c@@ -257,7 +257,7 @@ static void mtk_smi_larb_config_port_gen2_general(struct device *dev) if (MTK_SMI_CAPS(flags_general, MTK_SMI_FLAG_SW_FLAG)) writel_relaxed(SMI_LARB_SW_FLAG_1, larb->base + SMI_LARB_SW_FLAG); - for (i = 0; i < SMI_LARB_PORT_NR_MAX && larbostd && !!larbostd[i]; i++) + for (i = 0; i < SMI_LARB_PORT_NR_MAX && larb->larb_gen->ostd && !!larbostd[i]; i++) writel_relaxed(larbostd[i], larb->base + SMI_LARB_OSTDL_PORTx(i));
The code does not look good. You have already a dereference at line 244: const u8 *larbostd = larb->larb_gen->ostd[larb->larbid]; You are not fixing the NULL pointer dereference.
for_each_set_bit(i, (unsigned long *)larb->mmu, 32) {Best regards, Krzysztof _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel