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charset="utf-8" A process can disable access to the alternate signal stack and still expect signals to be delivered correctly. handle_signal() updates the PKRU value to enable access to the altstack, and makes sure that the value on the sigframe is the user-defined PKRU value so that it is correctly restored. However, in sigreturn(), restore_altstack() needs read access to the altstack. But the PKRU has already been restored from the sigframe (in restore_sigcontext()) which will disable access to the altstack, resulting in a SIGSEGV. Fix this by restoring altstack before restoring PKRU. Signed-off-by: Aruna Ramakrishna --- arch/x86/kernel/signal_32.c | 4 ++-- arch/x86/kernel/signal_64.c | 6 +++--- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c index b437d02ecfd7..348e855cecc6 100644 --- a/arch/x86/kernel/signal_32.c +++ b/arch/x86/kernel/signal_32.c @@ -160,10 +160,10 @@ SYSCALL32_DEFINE0(rt_sigreturn) =20 set_current_blocked(&set); =20 - if (!ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext)) + if (restore_altstack32(&frame->uc.uc_stack)) goto badframe; =20 - if (restore_altstack32(&frame->uc.uc_stack)) + if (!ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext)) goto badframe; =20 return regs->ax; diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c index ccfb7824ab2c..c5cf01898e83 100644 --- a/arch/x86/kernel/signal_64.c +++ b/arch/x86/kernel/signal_64.c @@ -260,13 +260,13 @@ SYSCALL_DEFINE0(rt_sigreturn) =20 set_current_blocked(&set); =20 - if (!restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) + if (restore_altstack(&frame->uc.uc_stack)) goto badframe; =20 - if (restore_signal_shadow_stack()) + if (!restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) goto badframe; =20 - if (restore_altstack(&frame->uc.uc_stack)) + if (restore_signal_shadow_stack()) goto badframe; =20 return regs->ax; --=20 2.39.3