Commit 1005c2d3 authored Jan 26, 2022 by Andy Lutomirski Committed by Zheng Zengkai Jan 26, 2022

x86/fpu: Add address range checks to copy_user_to_xstate()

mainline inclusion
from mainline-v5.13-rc7
commit f72a249b
category: feature
feature: milan cpu
bugzilla: https://gitee.com/openeuler/kernel/issues/I4M9PB


CVE: NA

--------------------------------

copy_user_to_xstate() uses __copy_from_user(), which provides a negligible
speedup.  Fortunately, both call sites are at least almost correct.

__fpu__restore_sig() checks access_ok() with xstate_sigframe_size()
length and ptrace regset access uses fpu_user_xstate_size. These should
be valid upper bounds on the length, so, at worst, this would cause
spurious failures and not accesses to kernel memory.

Nonetheless, this is far more fragile than necessary and none of these
callers are in a hotpath.

Use copy_from_user() instead.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Rik van Riel <riel@surriel.com>
Link: https://lkml.kernel.org/r/20210608144346.140254130@linutronix.de


Reviewed-by: Yunfeng Ye <yeyunfeng@huawei.com>
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>

parent eeabdc14

arch/x86/kernel/fpu/xstate.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -1242,7 +1242,7 @@ int copy_user_to_xstate(struct xregs_state xsave, const void __user ubuf)
		offset = offsetof(struct xregs_state, header);
		size = sizeof(hdr);

		if (__copy_from_user(&hdr, ubuf + offset, size))
		if (copy_from_user(&hdr, ubuf + offset, size))
		return -EFAULT;

		if (validate_user_xstate_header(&hdr))
		@@ -1257,7 +1257,7 @@ int copy_user_to_xstate(struct xregs_state xsave, const void __user ubuf)
		offset = xstate_offsets[i];
		size = xstate_sizes[i];

		if (__copy_from_user(dst, ubuf + offset, size))
		if (copy_from_user(dst, ubuf + offset, size))
		return -EFAULT;
		}
		}
		@@ -1265,7 +1265,7 @@ int copy_user_to_xstate(struct xregs_state xsave, const void __user ubuf)
		if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
		offset = offsetof(struct fxregs_state, mxcsr);
		size = MXCSR_AND_FLAGS_SIZE;
		if (__copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size))
		if (copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size))
		return -EFAULT;
		}