[PATCH 5.17 577/772] iommu/mediatek: Fix NULL pointer dereference when printing dev_name

Greg Kroah-Hartman
2022-06-07T21:31:53Z

From: Miles Chen <miles.chen@mediatek.com>

[ Upstream commit de78657e16f41417da9332f09c2d67d100096939 ]

When larbdev is NULL (in the case I hit, the node is incorrectly set
iommus = <&iommu NUM>), it will cause device_link_add() fail and
kernel crashes when we try to print dev_name(larbdev).

Let's fail the probe if a larbdev is NULL to avoid invalid inputs from
dts.

It should work for normal correct setting and avoid the crash caused
by my incorrect setting.

Error log:
[ 18.189042][ T301] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000050
...
[ 18.344519][ T301] pstate: a0400005 (NzCv daif +PAN -UAO)
[ 18.345213][ T301] pc : mtk_iommu_probe_device+0xf8/0x118 [mtk_iommu]
[ 18.346050][ T301] lr : mtk_iommu_probe_device+0xd0/0x118 [mtk_iommu]
[ 18.346884][ T301] sp : ffffffc00a5635e0
[ 18.347392][ T301] x29: ffffffc00a5635e0 x28: ffffffd44a46c1d8
[ 18.348156][ T301] x27: ffffff80c39a8000 x26: ffffffd44a80cc38
[ 18.348917][ T301] x25: 0000000000000000 x24: ffffffd44a80cc38
[ 18.349677][ T301] x23: ffffffd44e4da4c6 x22: ffffffd44a80cc38
[ 18.350438][ T301] x21: ffffff80cecd1880 x20: 0000000000000000
[ 18.351198][ T301] x19: ffffff80c439f010 x18: ffffffc00a50d0c0
[ 18.351959][ T301] x17: ffffffffffffffff x16: 0000000000000004
[ 18.352719][ T301] x15: 0000000000000004 x14: ffffffd44eb5d420
[ 18.353480][ T301] x13: 0000000000000ad2 x12: 0000000000000003
[ 18.354241][ T301] x11: 00000000fffffad2 x10: c0000000fffffad2
[ 18.355003][ T301] x9 : a0d288d8d7142d00 x8 : a0d288d8d7142d00
[ 18.355763][ T301] x7 : ffffffd44c2bc640 x6 : 0000000000000000
[ 18.356524][ T301] x5 : 0000000000000080 x4 : 0000000000000001
[ 18.357284][ T301] x3 : 0000000000000000 x2 : 0000000000000005
[ 18.358045][ T301] x1 : 0000000000000000 x0 : 0000000000000000
[ 18.360208][ T301] Hardware name: MT6873 (DT)
[ 18.360771][ T301] Call trace:
[ 18.361168][ T301] dump_backtrace+0xf8/0x1f0
[ 18.361737][ T301] dump_stack_lvl+0xa8/0x11c
[ 18.362305][ T301] dump_stack+0x1c/0x2c
[ 18.362816][ T301] mrdump_common_die+0x184/0x40c [mrdump]
[ 18.363575][ T301] ipanic_die+0x24/0x38 [mrdump]
[ 18.364230][ T301] atomic_notifier_call_chain+0x128/0x2b8
[ 18.364937][ T301] die+0x16c/0x568
[ 18.365394][ T301] __do_kernel_fault+0x1e8/0x214
[ 18.365402][ T301] do_page_fault+0xb8/0x678
[ 18.366934][ T301] do_translation_fault+0x48/0x64
[ 18.368645][ T301] do_mem_abort+0x68/0x148
[ 18.368652][ T301] el1_abort+0x40/0x64
[ 18.368660][ T301] el1h_64_sync_handler+0x54/0x88
[ 18.368668][ T301] el1h_64_sync+0x68/0x6c
[ 18.368673][ T301] mtk_iommu_probe_device+0xf8/0x118 [mtk_iommu]
...

Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Yong Wu <yong.wu@mediatek.com>
Reported-by: kernel test robot <lkp@intel.com>
Fixes: 635319a4a744 ("media: iommu/mediatek: Add device_link between the consumer and the larb devices")
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Reviewed-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220505132731.21628-1-miles.chen@mediatek.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iommu/mtk_iommu.c | 6 ++++++
drivers/iommu/mtk_iommu_v1.c | 7 +++++++
2 files changed, 13 insertions(+)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 9b3ded518f83..2ae46fa6b3de 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -586,6 +586,9 @@ static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
* All the ports in each a device should be in the same larbs.
*/
larbid = MTK_M4U_TO_LARB(fwspec->ids[0]);
+ if (larbid >= MTK_LARB_NR_MAX)
+ return ERR_PTR(-EINVAL);
+
for (i = 1; i < fwspec->num_ids; i++) {
larbidx = MTK_M4U_TO_LARB(fwspec->ids[i]);
if (larbid != larbidx) {
@@ -595,6 +598,9 @@ static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
}
}
larbdev = data->larb_imu[larbid].dev;
+ if (!larbdev)
+ return ERR_PTR(-EINVAL);
+
link = device_link_add(dev, larbdev,
DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
if (!link)
diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index bc7ee90b9373..254530ad6c48 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -80,6 +80,7 @@
/* MTK generation one iommu HW only support 4K size mapping */
#define MT2701_IOMMU_PAGE_SHIFT 12
#define MT2701_IOMMU_PAGE_SIZE (1UL << MT2701_IOMMU_PAGE_SHIFT)
+#define MT2701_LARB_NR_MAX 3

/*
* MTK m4u support 4GB iova address space, and only support 4K page
@@ -457,6 +458,9 @@ static struct iommu_device *mtk_iommu_probe_device(struct device *dev)

/* Link the consumer device with the smi-larb device(supplier) */
larbid = mt2701_m4u_to_larb(fwspec->ids[0]);
+ if (larbid >= MT2701_LARB_NR_MAX)
+ return ERR_PTR(-EINVAL);
+
for (idx = 1; idx < fwspec->num_ids; idx++) {
larbidx = mt2701_m4u_to_larb(fwspec->ids[idx]);
if (larbid != larbidx) {
@@ -467,6 +471,9 @@ static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
}

larbdev = data->larb_imu[larbid].dev;
+ if (!larbdev)
+ return ERR_PTR(-EINVAL);
+
link = device_link_add(dev, larbdev,
DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
if (!link)
--
2.35.1