On 2016/3/7 15:04, Seshagiri Holi wrote:
Hi Shawn,
I am not sure how why blkdev_roset is iocl function call is landing in mmc_blk_ioctl. Could it be a IOCTL mapping issue ?
Regards
Seshagiri
Really no.
blkdev_ioctl-> case BLKROSET ->
blkdev_roset -> __blkdev_driver_ioctl ->disk->fops->ioctl
If mmc_blk_ioctl return -EINVAL, that will fails
the check of !is_unrecognized_ioctl. Then the code will continue
to work. But commit: a5f5774c55a2 ("mmc: block: Add new ioctl to send
multi commands") changes the behaviour to check the cmd(BLKROSET) with
CAP_SYS_RAWIO firstly. So blkdev_ioctl finally get -EPERM instead of
-EINVAL. So the result you can find:
remount of /system failed;
couldn't make block device writable: Operation not permitted
openat(AT_FDCWD, "/dev/block/platform/ff420000.dwmmc/by-name/system",
O_RDONLY) = 3 ioctl(3, BLKROSET, 0) = -1 EPERM (Operation not permitted)
-----Original Message-----
From: Shawn Lin [mailto:shawn.lin@xxxxxxxxxxxxxx]
Sent: Monday, March 07, 2016 11:54 AM
To: Ulf Hansson
Cc: Seshagiri Holi; Jonathan Hunter; Shawn Lin; stable@xxxxxxxxxxxxxxx; #@263.net; 4.4.x@xxxxxxx
Subject: [PATCH] mmc: block: fix ABI regression of mmc_blk_ioctl
We should return -EINVAL if cmd is not MMC_IOC_CMD or MMC_IOC_MULTI_CMD, otherwise blkdev_roset will return -EPERM.
Android-adb calls make_block_device_writable with ioctl(BLKROSET), which will return error, make remount failed:
remount of /system failed;
couldn't make block device writable: Operation not permitted
openat(AT_FDCWD, "/dev/block/platform/ff420000.dwmmc/by-name/system", O_RDONLY) = 3 ioctl(3, BLKROSET, 0) = -1 EPERM (Operation not permitted)
Fixes: a5f5774c55a2 ("mmc: block: Add new ioctl to send multi commands")
Cc: <stable@xxxxxxxxxxxxxxx> # 4.4.x
Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
---
drivers/mmc/card/block.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c index 47bc87d..170f099 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -688,6 +688,9 @@ cmd_err:
static int mmc_blk_ioctl(struct block_device *bdev, fmode_t mode,
unsigned int cmd, unsigned long arg)
{
+ if (cmd != MMC_IOC_CMD && cmd != MMC_IOC_MULTI_CMD)
+ return -EINVAL;
+
/*
* The caller must have CAP_SYS_RAWIO, and must be calling this on the
* whole block device, not on a partition. This prevents overspray
--
2.3.7
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Best Regards
Shawn Lin
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