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authorYu-cheng Yu <yu-cheng.yu@intel.com>2016-11-17 09:11:35 -0800
committerIngo Molnar <mingo@kernel.org>2016-11-21 10:38:35 +0100
commitb22cbe404a9cc3c7949e380fa1861e31934c8978 (patch)
treeb88f02a3b34c3d138a96b9f6174ab66e643c3af0
parented68d7e9b9cfb64f3045ffbcb108df03c09a0f98 (diff)
x86/fpu: Fix invalid FPU ptrace state after execve()
Robert O'Callahan reported that after an execve PTRACE_GETREGSET NT_X86_XSTATE continues to return the pre-exec register values until the exec'ed task modifies FPU state. The test code is at: https://bugzilla.redhat.com/attachment.cgi?id=1164286. What is happening is fpu__clear() does not properly clear fpstate. Fix it by doing just that. Reported-by: Robert O'Callahan <robert@ocallahan.org> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> Cc: <stable@vger.kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@suse.de> Cc: David Hansen <dave.hansen@linux.intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi V. Shankar <ravi.v.shankar@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1479402695-6553-1-git-send-email-yu-cheng.yu@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/kernel/fpu/core.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 47004010ad5d..ebb4e95fbd74 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -521,14 +521,14 @@ void fpu__clear(struct fpu *fpu)
{
WARN_ON_FPU(fpu != &current->thread.fpu); /* Almost certainly an anomaly */
- if (!use_eager_fpu() || !static_cpu_has(X86_FEATURE_FPU)) {
- /* FPU state will be reallocated lazily at the first use. */
- fpu__drop(fpu);
- } else {
- if (!fpu->fpstate_active) {
- fpu__activate_curr(fpu);
- user_fpu_begin();
- }
+ fpu__drop(fpu);
+
+ /*
+ * Make sure fpstate is cleared and initialized.
+ */
+ if (static_cpu_has(X86_FEATURE_FPU)) {
+ fpu__activate_curr(fpu);
+ user_fpu_begin();
copy_init_fpstate_to_fpregs();
}
}