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sched_getattr: port to copy_struct_to_user

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sched_getattr(2) doesn't care about trailing non-zero bytes in the
(ksize > usize) case, so just use copy_struct_to_user() without checking
ignored_trailing.

Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Link: https://lore.kernel.org/r/20241010-extensible-structs-check_fields-v3-2-d2833dfe6edd@cyphar.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Aleksa Sarai
2024-10-10 07:40:35 +11:00
committed by Christian Brauner
parent 424a55a4a9
commit 112cca098a
1 changed files with 2 additions and 40 deletions
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42
kernel/sched/syscalls.c
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@@ -1076,45 +1076,6 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
return copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
}
/*
* Copy the kernel size attribute structure (which might be larger
* than what user-space knows about) to user-space.
*
* Note that all cases are valid: user-space buffer can be larger or
* smaller than the kernel-space buffer. The usual case is that both
* have the same size.
*/
static int
sched_attr_copy_to_user(struct sched_attr __user *uattr,
struct sched_attr *kattr,
unsigned int usize)
{
unsigned int ksize = sizeof(*kattr);
if (!access_ok(uattr, usize))
return -EFAULT;
/*
* sched_getattr() ABI forwards and backwards compatibility:
*
* If usize == ksize then we just copy everything to user-space and all is good.
*
* If usize < ksize then we only copy as much as user-space has space for,
* this keeps ABI compatibility as well. We skip the rest.
*
* If usize > ksize then user-space is using a newer version of the ABI,
* which part the kernel doesn't know about. Just ignore it - tooling can
* detect the kernel's knowledge of attributes from the attr->size value
* which is set to ksize in this case.
*/
kattr->size = min(usize, ksize);
if (copy_to_user(uattr, kattr, kattr->size))
return -EFAULT;
return 0;
}
/**
* sys_sched_getattr - similar to sched_getparam, but with sched_attr
* @pid: the pid in question.
@@ -1159,7 +1120,8 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
#endif
}
return sched_attr_copy_to_user(uattr, &kattr, usize);
kattr.size = min(usize, sizeof(kattr));
return copy_struct_to_user(uattr, usize, &kattr, sizeof(kattr), NULL);
}
#ifdef CONFIG_SMP