With gcc 4.1.2:
drivers/mmc/core/block.c: In function ‘mmc_blk_ioctl_cmd_issue’:
drivers/mmc/core/block.c:630: warning: ‘ioc_err’ may be used uninitialized in this function
Indeed, if mq_rq->ioc_count is zero, an uninitialized value will be
stored in mq_rq->drv_op_result and passed to blk_end_request_all().
Can mq_rq->ioc_count be zero?
- mmc_blk_ioctl_cmd() sets ioc_count to 1, so this is safe,
- mmc_blk_ioctl_multi_cmd() obtains ioc_count from user space in
response to the MMC_IOC_MULTI_CMD ioctl, and does allow zero.
To avoid returning an uninitialized value, and as it is pointless to do
all this work when the MMC_IOC_MULTI_CMD ioctl is used with zero
entries, check for this early in mmc_blk_ioctl_multi_cmd(), and return
zero, like was returned before.
Fixes: 3ecd8cf23f88d5df ("mmc: block: move multi-ioctl() to use block layer")
Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
---
Should mmc_blk_ioctl_multi_cmd() return -EINVAL instead for this case?
That would change behavior as seen from userspace, though.
Feel free to fold in the previous patch if deemed appropriate.
v2:
- No changes.
---
drivers/mmc/core/block.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 4920ea1ece38a9b6..e0363223996e6096 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -637,6 +637,9 @@ static int mmc_blk_ioctl_multi_cmd(struct block_device *bdev,
sizeof(num_of_cmds)))
return -EFAULT;
+ if (!num_of_cmds)
+ return 0;
+
if (num_of_cmds > MMC_IOC_MAX_CMDS)
return -EINVAL;
--
2.7.4
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