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Subject[ 14/72] mmc: core: check for zero length ioctl data
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Rudholm <johan.rudholm@stericsson.com>

commit 4d6144de8ba263eb3691a737c547e5b2fdc45287 upstream.

If the read or write buffer size associated with the command sent
through the mmc_blk_ioctl is zero, do not prepare data buffer.

This enables a ioctl(2) call to for instance send a MMC_SWITCH to set
a byte in the ext_csd.

Signed-off-by: Johan Rudholm <johan.rudholm@stericsson.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/mmc/card/block.c | 82 +++++++++++++++++++++++++----------------------
1 file changed, 45 insertions(+), 37 deletions(-)

--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -266,6 +266,9 @@ static struct mmc_blk_ioc_data *mmc_blk_
goto idata_err;
}

+ if (!idata->buf_bytes)
+ return idata;
+
idata->buf = kzalloc(idata->buf_bytes, GFP_KERNEL);
if (!idata->buf) {
err = -ENOMEM;
@@ -312,25 +315,6 @@ static int mmc_blk_ioctl_cmd(struct bloc
if (IS_ERR(idata))
return PTR_ERR(idata);

- cmd.opcode = idata->ic.opcode;
- cmd.arg = idata->ic.arg;
- cmd.flags = idata->ic.flags;
-
- data.sg = &sg;
- data.sg_len = 1;
- data.blksz = idata->ic.blksz;
- data.blocks = idata->ic.blocks;
-
- sg_init_one(data.sg, idata->buf, idata->buf_bytes);
-
- if (idata->ic.write_flag)
- data.flags = MMC_DATA_WRITE;
- else
- data.flags = MMC_DATA_READ;
-
- mrq.cmd = &cmd;
- mrq.data = &data;
-
md = mmc_blk_get(bdev->bd_disk);
if (!md) {
err = -EINVAL;
@@ -343,6 +327,48 @@ static int mmc_blk_ioctl_cmd(struct bloc
goto cmd_done;
}

+ cmd.opcode = idata->ic.opcode;
+ cmd.arg = idata->ic.arg;
+ cmd.flags = idata->ic.flags;
+
+ if (idata->buf_bytes) {
+ data.sg = &sg;
+ data.sg_len = 1;
+ data.blksz = idata->ic.blksz;
+ data.blocks = idata->ic.blocks;
+
+ sg_init_one(data.sg, idata->buf, idata->buf_bytes);
+
+ if (idata->ic.write_flag)
+ data.flags = MMC_DATA_WRITE;
+ else
+ data.flags = MMC_DATA_READ;
+
+ /* data.flags must already be set before doing this. */
+ mmc_set_data_timeout(&data, card);
+
+ /* Allow overriding the timeout_ns for empirical tuning. */
+ if (idata->ic.data_timeout_ns)
+ data.timeout_ns = idata->ic.data_timeout_ns;
+
+ if ((cmd.flags & MMC_RSP_R1B) == MMC_RSP_R1B) {
+ /*
+ * Pretend this is a data transfer and rely on the
+ * host driver to compute timeout. When all host
+ * drivers support cmd.cmd_timeout for R1B, this
+ * can be changed to:
+ *
+ * mrq.data = NULL;
+ * cmd.cmd_timeout = idata->ic.cmd_timeout_ms;
+ */
+ data.timeout_ns = idata->ic.cmd_timeout_ms * 1000000;
+ }
+
+ mrq.data = &data;
+ }
+
+ mrq.cmd = &cmd;
+
mmc_claim_host(card->host);

if (idata->ic.is_acmd) {
@@ -351,24 +377,6 @@ static int mmc_blk_ioctl_cmd(struct bloc
goto cmd_rel_host;
}

- /* data.flags must already be set before doing this. */
- mmc_set_data_timeout(&data, card);
- /* Allow overriding the timeout_ns for empirical tuning. */
- if (idata->ic.data_timeout_ns)
- data.timeout_ns = idata->ic.data_timeout_ns;
-
- if ((cmd.flags & MMC_RSP_R1B) == MMC_RSP_R1B) {
- /*
- * Pretend this is a data transfer and rely on the host driver
- * to compute timeout. When all host drivers support
- * cmd.cmd_timeout for R1B, this can be changed to:
- *
- * mrq.data = NULL;
- * cmd.cmd_timeout = idata->ic.cmd_timeout_ms;
- */
- data.timeout_ns = idata->ic.cmd_timeout_ms * 1000000;
- }
-
mmc_wait_for_req(card->host, &mrq);

if (cmd.error) {



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