[PATCH AUTOSEL 4.14 38/43] libata: fix using DMA buffers on stack

Sasha Levin
2019-04-22T19:57:20Z

From: raymond pang <raymondpangxd@gmail.com>

[ Upstream commit dd08a8d9a66de4b54575c294a92630299f7e0fe7 ]

When CONFIG_VMAP_STACK=y, __pa() returns incorrect physical address for
a stack virtual address. Stack DMA buffers must be avoided.

Signed-off-by: raymond pang <raymondpangxd@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
---
drivers/ata/libata-zpodd.c | 34 ++++++++++++++++++++++++----------
1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/ata/libata-zpodd.c b/drivers/ata/libata-zpodd.c
index b3ed8f9953a8..173e6f2dd9af 100644
--- a/drivers/ata/libata-zpodd.c
+++ b/drivers/ata/libata-zpodd.c
@@ -52,38 +52,52 @@ static int eject_tray(struct ata_device *dev)
/* Per the spec, only slot type and drawer type ODD can be supported */
static enum odd_mech_type zpodd_get_mech_type(struct ata_device *dev)
{
- char buf[16];
+ char *buf;
unsigned int ret;
- struct rm_feature_desc *desc = (void *)(buf + 8);
+ struct rm_feature_desc *desc;
struct ata_taskfile tf;
static const char cdb[] = { GPCMD_GET_CONFIGURATION,
2, /* only 1 feature descriptor requested */
0, 3, /* 3, removable medium feature */
0, 0, 0,/* reserved */
- 0, sizeof(buf),
+ 0, 16,
0, 0, 0,
};

+ buf = kzalloc(16, GFP_KERNEL);
+ if (!buf)
+ return ODD_MECH_TYPE_UNSUPPORTED;
+ desc = (void *)(buf + 8);
+
ata_tf_init(dev, &tf);
tf.flags = ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
tf.command = ATA_CMD_PACKET;
tf.protocol = ATAPI_PROT_PIO;
- tf.lbam = sizeof(buf);
+ tf.lbam = 16;

ret = ata_exec_internal(dev, &tf, cdb, DMA_FROM_DEVICE,
- buf, sizeof(buf), 0);
- if (ret)
+ buf, 16, 0);
+ if (ret) {
+ kfree(buf);
return ODD_MECH_TYPE_UNSUPPORTED;
+ }

- if (be16_to_cpu(desc->feature_code) != 3)
+ if (be16_to_cpu(desc->feature_code) != 3) {
+ kfree(buf);
return ODD_MECH_TYPE_UNSUPPORTED;
+ }

- if (desc->mech_type == 0 && desc->load == 0 && desc->eject == 1)
+ if (desc->mech_type == 0 && desc->load == 0 && desc->eject == 1) {
+ kfree(buf);
return ODD_MECH_TYPE_SLOT;
- else if (desc->mech_type == 1 && desc->load == 0 && desc->eject == 1)
+ } else if (desc->mech_type == 1 && desc->load == 0 &&
+ desc->eject == 1) {
+ kfree(buf);
return ODD_MECH_TYPE_DRAWER;
- else
+ } else {
+ kfree(buf);
return ODD_MECH_TYPE_UNSUPPORTED;
+ }
}

/* Test if ODD is zero power ready by sense code */
--
2.19.1