@@ -300,13 +300,12 @@ static noinstr int error_context(struct mce *m, struct pt_regs *regs)
copy_user = is_copy_from_user(regs);
instrumentation_end();
- switch (fixup_type) {
- case EX_TYPE_UACCESS:
- if (!copy_user)
- return IN_KERNEL;
- m->kflags |= MCE_IN_KERNEL_COPYIN;
- fallthrough;
+ if (copy_user) {
+ m->kflags |= MCE_IN_KERNEL_COPYIN | MCE_IN_KERNEL_RECOV;
+ return IN_KERNEL_RECOV;
+ }
+ switch (fixup_type) {
case EX_TYPE_FAULT_MCE_SAFE:
case EX_TYPE_DEFAULT_MCE_SAFE:
m->kflags |= MCE_IN_KERNEL_RECOV;
Commit 4c132d1d844a ("x86/futex: Remove .fixup usage") introduced a new extable fixup type, EX_TYPE_EFAULT_REG, and commit 4c132d1d844a ("x86/futex: Remove .fixup usage") updated the extable fixup type for copy-from-user operations, changing it from EX_TYPE_UACCESS to EX_TYPE_EFAULT_REG. The error context for copy-from-user operations no longer functions as an in-kernel recovery context. Consequently, the error context for copy-from-user operations no longer functions as an in-kernel recovery context, resulting in kernel panics with the message: "Machine check: Data load in unrecoverable area of kernel." To address this, it is crucial to identify if an error context involves a read operation from user memory. The function is_copy_from_user() can be utilized to determine: - the current operation is copy - when reading user memory When these conditions are met, is_copy_from_user() will return true, confirming that it is indeed a direct copy from user memory. This check is essential for correctly handling the context of errors in these operations without relying on the extable fixup types that previously allowed for in-kernel recovery. So, use is_copy_from_user() to determine if a context is copy user directly. Fixes: 4c132d1d844a ("x86/futex: Remove .fixup usage") Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com> Acked-by: Borislav Petkov (AMD) <bp@alien8.de> Tested-by: Tony Luck <tony.luck@intel.com> Cc: stable@vger.kernel.org --- arch/x86/kernel/cpu/mce/severity.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)