From: Andy Shevchenko andriy.shevchenko@linux.intel.com
[ 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 --- 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; }