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authorAndy Shevchenko <andriy.shevchenko@linux.intel.com>2020-09-15 15:58:16 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-10-07 08:02:54 +0200
commit115b0aed8b749e9435210d5b1d23ac16fa6658ef (patch)
treea6a09b41399896c8b188c11ded3f663ca69bba23
parentb4b93f8c92bbd870594c8e0a5b99c2c0640577dd (diff)
gpiolib: Fix line event handling in syscall compatible mode
[ 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@arndb.de> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Tested-by: Kent Gibson <warthog618@gmail.com> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--drivers/gpio/gpiolib.c34
1 files changed, 30 insertions, 4 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 4fa075d49fbc..6e813b13d698 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -836,6 +836,21 @@ static __poll_t lineevent_poll(struct file *filep,
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 file *filep,
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 file *filep,
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;
}