After a bit of poking around wondering why my 32-bit user-space can't
seem to send a proper ioctl(BLKPG) to an MTD on my 64-bit kernel
(ARM64), I noticed that struct blkpg_ioctl_arg is actually pretty
unsuitable for use in the ioctl() ABI, due to its use of raw pointers,
and its lack of alignment/packing restrictions (32-bit arch'es tend to
pack the 4 fields into 4 32-bit words, whereas 64-bit arch'es would add
padding after the third int, and make this 6 32-bit words).
Anyway, this means BLKPG deserves some special compat_ioctl handling. Do
the conversion in a small shim for MTD.
The same bug applies to block/ioctl.c, but I wanted to get some comments
first. I can send a non-RFC with the same approach for the block
subsystem. But then: which tree should it go in?
Tested only on MTD, with an ARM32 user space on an ARM64 kernel.
Signed-off-by: Brian Norris <computersforpe...@gmail.com>
---
drivers/mtd/mtdchar.c | 42 +++++++++++++++++++++++++++++++++---------
include/uapi/linux/blkpg.h | 10 ++++++++++
2 files changed, 43 insertions(+), 9 deletions(-)
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 55fa27ecf4e1..bf966be09e79 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -498,21 +498,17 @@ static int shrink_ecclayout(const struct nand_ecclayout
*from,
}
static int mtdchar_blkpg_ioctl(struct mtd_info *mtd,
- struct blkpg_ioctl_arg __user *arg)
+ struct blkpg_ioctl_arg *arg)
{
- struct blkpg_ioctl_arg a;
struct blkpg_partition p;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (copy_from_user(&a, arg, sizeof(struct blkpg_ioctl_arg)))
+ if (copy_from_user(&p, arg->data, sizeof(p)))
return -EFAULT;
- if (copy_from_user(&p, a.data, sizeof(struct blkpg_partition)))
- return -EFAULT;
-
- switch (a.op) {
+ switch (arg->op) {
case BLKPG_ADD_PARTITION:
/* Only master mtd device must be used to add partitions */
@@ -966,8 +962,13 @@ static int mtdchar_ioctl(struct file *file, u_int cmd,
u_long arg)
case BLKPG:
{
- ret = mtdchar_blkpg_ioctl(mtd,
- (struct blkpg_ioctl_arg __user *)arg);
+ struct blkpg_ioctl_arg __user *blk_arg = argp;
+ struct blkpg_ioctl_arg a;
+
+ if (copy_from_user(&a, blk_arg, sizeof(a)))
+ ret = -EFAULT;
+ else
+ ret = mtdchar_blkpg_ioctl(mtd, &a);
break;
}
@@ -1046,6 +1047,29 @@ static long mtdchar_compat_ioctl(struct file *file,
unsigned int cmd,
&buf_user->start);
break;
}
+
+ case BLKPG:
+ {
+ /* Convert from blkpg_compat_ioctl_arg to blkpg_ioctl_arg */
+ struct blkpg_compat_ioctl_arg __user *uarg = argp;
+ struct blkpg_compat_ioctl_arg arg;
+ struct blkpg_ioctl_arg a;
+
+ if (copy_from_user(&arg, uarg, sizeof(arg))) {
+ ret = -EFAULT;
+ break;
+ }
+
+ memset(&a, 0, sizeof(a));
+ a.op = arg.op;
+ a.flags = arg.flags;
+ a.datalen = arg.datalen;
+ a.data = compat_ptr(arg.data);
+
+ ret = mtdchar_blkpg_ioctl(mtd, &a);
+ break;
+ }
+
default:
ret = mtdchar_ioctl(file, cmd, (unsigned long)argp);
}
diff --git a/include/uapi/linux/blkpg.h b/include/uapi/linux/blkpg.h
index a8519446c111..0574147f4490 100644
--- a/include/uapi/linux/blkpg.h
+++ b/include/uapi/linux/blkpg.h
@@ -26,6 +26,7 @@
*/
#include <linux/compiler.h>
#include <linux/ioctl.h>
+#include <linux/compat.h>
#define BLKPG _IO(0x12,105)
@@ -37,6 +38,15 @@ struct blkpg_ioctl_arg {
void __user *data;
};
+#ifdef CONFIG_COMPAT
+struct blkpg_compat_ioctl_arg {
+ compat_int_t op;
+ compat_int_t flags;
+ compat_int_t datalen;
+ compat_uptr_t data;
+};
+#endif
+
/* The subfunctions (for the op field) */
#define BLKPG_ADD_PARTITION 1
#define BLKPG_DEL_PARTITION 2
--
2.5.0.457.gab17608
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