From: Andy Lutomirski luto@kernel.org
mainline inclusion from mainline-v5.13-rc7 commit f72a249b0ba85564c6bfa94d609a70567485a061 category: feature feature: milan cpu bugzilla: https://gitee.com/openeuler/kernel/issues/I4M9PB CVE: NA
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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 --- arch/x86/kernel/fpu/xstate.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 80836b94189e..6655e0df2fb7 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -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; }