From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
[ Upstream commit 5ad284ab3a01e2d6a89be2a8663ae76f4e617549 ]
The introduced line event handling ABI in the commit
61f922db7221 ("gpio: userspace ABI for reading GPIO line events")
missed the fact that 64-bit kernel may serve for 32-bit applications.
In such case the very first check in the lineevent_read() will fail
due to alignment differences.
To workaround this introduce lineevent_get_size() helper which returns actual
size of the structure in user space.
Fixes: 61f922db7221 ("gpio: userspace ABI for reading GPIO line events")
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
Tested-by: Kent Gibson <warthog618@xxxxxxxxx>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/gpio/gpiolib.c | 34 ++++++++++++++++++++++++++++++----
1 file changed, 30 insertions(+), 4 deletions(-)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -836,6 +836,21 @@ static __poll_t lineevent_poll(struct fi
return events;
}
+static ssize_t lineevent_get_size(void)
+{
+#ifdef __x86_64__
+ /* i386 has no padding after 'id' */
+ if (in_ia32_syscall()) {
+ struct compat_gpioeevent_data {
+ compat_u64 timestamp;
+ u32 id;
+ };
+
+ return sizeof(struct compat_gpioeevent_data);
+ }
+#endif
+ return sizeof(struct gpioevent_data);
+}
static ssize_t lineevent_read(struct file *filep,
char __user *buf,
@@ -845,9 +860,20 @@ static ssize_t lineevent_read(struct fil
struct lineevent_state *le = filep->private_data;
struct gpioevent_data ge;
ssize_t bytes_read = 0;
+ ssize_t ge_size;
int ret;
- if (count < sizeof(ge))
+ /*
+ * When compatible system call is being used the struct gpioevent_data,
+ * in case of at least ia32, has different size due to the alignment
+ * differences. Because we have first member 64 bits followed by one of
+ * 32 bits there is no gap between them. The only difference is the
+ * padding at the end of the data structure. Hence, we calculate the
+ * actual sizeof() and pass this as an argument to copy_to_user() to
+ * drop unneeded bytes from the output.
+ */
+ ge_size = lineevent_get_size();
+ if (count < ge_size)
return -EINVAL;
do {
@@ -883,10 +909,10 @@ static ssize_t lineevent_read(struct fil
break;
}
- if (copy_to_user(buf + bytes_read, &ge, sizeof(ge)))
+ if (copy_to_user(buf + bytes_read, &ge, ge_size))
return -EFAULT;
- bytes_read += sizeof(ge);
- } while (count >= bytes_read + sizeof(ge));
+ bytes_read += ge_size;
+ } while (count >= bytes_read + ge_size);
return bytes_read;
}
