The change is very straightforward, and takes advantage of the (very minor) efficiency improvements in copy_struct_{to,from}_user() -- that the memchr_inv() check is done on a buffer instead of one-at-at-time with get_user() or put_user().
Signed-off-by: Aleksa Sarai cyphar@cyphar.com --- kernel/sched/core.c | 85 ++++++--------------------------------------- 1 file changed, 10 insertions(+), 75 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 010d578118d6..2f58b07d3468 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4900,9 +4900,6 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a u32 size; int ret;
- if (!access_ok(uattr, SCHED_ATTR_SIZE_VER0)) - return -EFAULT; - /* Zero the full structure, so that a short copy will be nice: */ memset(attr, 0, sizeof(*attr));
@@ -4910,45 +4907,19 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a if (ret) return ret;
- /* Bail out on silly large: */ - if (size > PAGE_SIZE) - goto err_size; - /* ABI compatibility quirk: */ if (!size) size = SCHED_ATTR_SIZE_VER0; - if (size < SCHED_ATTR_SIZE_VER0) goto err_size;
- /* - * If we're handed a bigger struct than we know of, - * ensure all the unknown bits are 0 - i.e. new - * user-space does not rely on any kernel feature - * extensions we dont know about yet. - */ - if (size > sizeof(*attr)) { - unsigned char __user *addr; - unsigned char __user *end; - unsigned char val; - - addr = (void __user *)uattr + sizeof(*attr); - end = (void __user *)uattr + size; - - for (; addr < end; addr++) { - ret = get_user(val, addr); - if (ret) - return ret; - if (val) - goto err_size; - } - size = sizeof(*attr); + ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size); + if (ret) { + if (ret == -E2BIG) + goto err_size; + return ret; }
- ret = copy_from_user(attr, uattr, size); - if (ret) - return -EFAULT; - if ((attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) && size < SCHED_ATTR_SIZE_VER1) return -EINVAL; @@ -5105,51 +5076,15 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) return retval; }
-static int sched_read_attr(struct sched_attr __user *uattr, - struct sched_attr *attr, - unsigned int usize) -{ - int ret; - - if (!access_ok(uattr, usize)) - return -EFAULT; - - /* - * If we're handed a smaller struct than we know of, - * ensure all the unknown bits are 0 - i.e. old - * user-space does not get uncomplete information. - */ - if (usize < sizeof(*attr)) { - unsigned char *addr; - unsigned char *end; - - addr = (void *)attr + usize; - end = (void *)attr + sizeof(*attr); - - for (; addr < end; addr++) { - if (*addr) - return -EFBIG; - } - - attr->size = usize; - } - - ret = copy_to_user(uattr, attr, attr->size); - if (ret) - return -EFAULT; - - return 0; -} - /** * sys_sched_getattr - similar to sched_getparam, but with sched_attr * @pid: the pid in question. * @uattr: structure containing the extended parameters. - * @size: sizeof(attr) for fwd/bwd comp. + * @usize: sizeof(attr) for fwd/bwd comp. * @flags: for future extension. */ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, - unsigned int, size, unsigned int, flags) + unsigned int, usize, unsigned int, flags) { struct sched_attr attr = { .size = sizeof(struct sched_attr), @@ -5157,8 +5092,8 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, struct task_struct *p; int retval;
- if (!uattr || pid < 0 || size > PAGE_SIZE || - size < SCHED_ATTR_SIZE_VER0 || flags) + if (!uattr || pid < 0 || usize > PAGE_SIZE || + usize < SCHED_ATTR_SIZE_VER0 || flags) return -EINVAL;
rcu_read_lock(); @@ -5188,7 +5123,7 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
rcu_read_unlock();
- retval = sched_read_attr(uattr, &attr, size); + retval = copy_struct_to_user(uattr, usize, &attr, sizeof(attr)); return retval;
out_unlock: