From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Ulf Hansson <ulf.hansson@linaro.org>,
Linus Walleij <linus.walleij@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
Geert Uytterhoeven <geert@linux-m68k.org>
Subject: [PATCH v2 2/2] mmc: block: Let MMC_IOC_MULTI_CMD return zero again for zero entries
Date: Wed, 5 Jul 2017 17:09:42 +0200 [thread overview]
Message-ID: <1499267382-28438-2-git-send-email-geert@linux-m68k.org> (raw)
In-Reply-To: <1499267382-28438-1-git-send-email-geert@linux-m68k.org>
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@linux-m68k.org>
---
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
next prev parent reply other threads:[~2017-07-05 15:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-05 15:09 [PATCH v2 1/2] mmc: block: Initialize ret in mmc_blk_issue_drv_op() for MMC_DRV_OP_IOCTL Geert Uytterhoeven
2017-07-05 15:09 ` Geert Uytterhoeven [this message]
2017-07-11 14:44 ` [PATCH v2 2/2] mmc: block: Let MMC_IOC_MULTI_CMD return zero again for zero entries Ulf Hansson
2017-07-11 14:44 ` [PATCH v2 1/2] mmc: block: Initialize ret in mmc_blk_issue_drv_op() for MMC_DRV_OP_IOCTL Ulf Hansson
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