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Commit c2ba8f41 authored by Aleksa Sarai's avatar Aleksa Sarai Committed by Christian Brauner
Browse files

perf_event_open: switch to copy_struct_from_user() 



Switch perf_event_open() syscall from it's own copying
struct perf_event_attr from userspace to the new dedicated
copy_struct_from_user() helper.

The change is very straightforward, and helps unify the syscall
interface for struct-from-userspace syscalls.

Signed-off-by: default avatarAleksa Sarai <cyphar@cyphar.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
[christian.brauner@ubuntu.com: improve commit message]
Link: https://lore.kernel.org/r/20191001011055.19283-5-cyphar@cyphar.com


Signed-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
parent dff3a85f

kernel/events/core.c

+9 −38
Original line number Diff line number Diff line
@@ -10586,54 +10586,25 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr, 
	u32 size;

	int ret;



	if (!access_ok(uattr, PERF_ATTR_SIZE_VER0))

		return -EFAULT;



	/*

	 * zero the full structure, so that a short copy will be nice.

	 */

	/* Zero the full structure, so that a short copy will be nice. */

	memset(attr, 0, sizeof(*attr));



	ret = get_user(size, &uattr->size);

	if (ret)

		return ret;



	if (size > PAGE_SIZE)	/* silly large */

		goto err_size;



	if (!size)		/* abi compat */

	/* ABI compatibility quirk: */

	if (!size)

		size = PERF_ATTR_SIZE_VER0;



	if (size < PERF_ATTR_SIZE_VER0)

	if (size < PERF_ATTR_SIZE_VER0 || size > PAGE_SIZE)

		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)

	ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size);

	if (ret) {

		if (ret == -E2BIG)

			goto err_size;

		return ret;

	}

		size = sizeof(*attr);

	}



	ret = copy_from_user(attr, uattr, size);

	if (ret)

		return -EFAULT;



	attr->size = size;