@@ -168,8 +168,15 @@ static inline bool save_xstate_epilog(void __user *buf, int ia32_frame,
static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf, u32 pkru)
{
- if (use_xsave())
- return xsave_to_user_sigframe(buf);
+ int err = 0;
+
+ if (use_xsave()) {
+ err = xsave_to_user_sigframe(buf);
+ if (!err)
+ err = update_pkru_in_sigframe(buf, pkru);
+ return err;
+ }
+
if (use_fxsr())
return fxsave_to_user_sigframe((struct fxregs_state __user *) buf);
else
@@ -102,7 +102,7 @@ get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size,
unsigned long math_size = 0;
unsigned long sp = regs->sp;
unsigned long buf_fx = 0;
- u32 pkru = read_pkru();
+ u32 pkru;
/* redzone */
if (!ia32_frame)
@@ -157,9 +157,17 @@ get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size,
return (void __user *)-1L;
}
+ /* Update PKRU to enable access to the alternate signal stack. */
+ pkru = sig_prepare_pkru();
/* save i387 and extended state */
- if (!copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size, pkru))
+ if (!copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size, pkru)) {
+ /*
+ * Restore PKRU to the original, user-defined value; disable
+ * extra pkeys enabled for the alternate signal stack, if any.
+ */
+ write_pkru(pkru);
return (void __user *)-1L;
+ }
return (void __user *)sp;
}
If the alternate signal stack is protected by a different pkey than the current execution stack, copying xsave data to the sigaltstack will fail if its pkey is not enabled. We do not know which pkey was used by the application for the sigaltstack, so enable all pkeys before xsave so that the signal handler accessibility is not dictated by the PKRU value that the thread sets up. But this updated PKRU value is also pushed onto the sigframe, so overwrite that with the original, user-defined PKRU value so that the value restored from sigcontext does not have the extra pkey enabled. Signed-off-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com> --- arch/x86/kernel/fpu/signal.c | 11 +++++++++-- arch/x86/kernel/signal.c | 12 ++++++++++-- 2 files changed, 19 insertions(+), 4 deletions(-)