diff options
author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2020-09-15 15:58:16 +0300 |
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committer | Bartosz Golaszewski <bgolaszewski@baylibre.com> | 2020-09-17 12:03:37 +0200 |
commit | 5ad284ab3a01e2d6a89be2a8663ae76f4e617549 (patch) | |
tree | 42a4ed0dc765611cecc4fc00a2e54604d5965c60 /drivers/gpio | |
parent | 1b02d9e770cd7087f34c743f85ccf5ea8372b047 (diff) | |
download | linux-5ad284ab3a01e2d6a89be2a8663ae76f4e617549.tar.bz2 |
gpiolib: Fix line event handling in syscall compatible mode
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>
Diffstat (limited to 'drivers/gpio')
-rw-r--r-- | drivers/gpio/gpiolib-cdev.c | 34 |
1 files changed, 30 insertions, 4 deletions
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index e6c9b78adfc2..76c36b05aef6 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -423,6 +423,21 @@ static __poll_t lineevent_poll(struct file *file, 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 *file, char __user *buf, @@ -432,9 +447,20 @@ static ssize_t lineevent_read(struct file *file, struct lineevent_state *le = file->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 { @@ -470,10 +496,10 @@ static ssize_t lineevent_read(struct file *file, 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; } |