Clear the padding when returning context to the usermode, for

MI ucontext_t and x86 MD parts.
Kernel allocates the structures on the stack, and not clearing
reserved fields and paddings causes leakage.

Noted and discussed with:	bde
MFC after:	2 weeks

4 files changed, 35 insertions, 1 deletions

diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index a6068b5..d350aa6 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -331,6 +331,9 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	fpstate_drop(td);
 	sf.sf_uc.uc_mcontext.mc_fsbase = pcb->pcb_fsbase;
 	sf.sf_uc.uc_mcontext.mc_gsbase = pcb->pcb_gsbase;
+	bzero(sf.sf_uc.uc_mcontext.mc_spare,
+	    sizeof(sf.sf_uc.uc_mcontext.mc_spare));
+	bzero(sf.sf_uc.__spare__, sizeof(sf.sf_uc.__spare__));
 
 	/* Allocate space for the signal handler context. */
 	if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
@@ -352,6 +355,7 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	/* Build the argument list for the signal handler. */
 	regs->tf_rdi = sig;			/* arg 1 in %rdi */
 	regs->tf_rdx = (register_t)&sfp->sf_uc;	/* arg 3 in %rdx */
+	bzero(&sf.sf_si, sizeof(sf.sf_si));
 	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
 		/* Signal handler installed with SA_SIGINFO. */
 		regs->tf_rsi = (register_t)&sfp->sf_si;	/* arg 2 in %rsi */
@@ -2043,6 +2047,7 @@ get_mcontext(struct thread *td, mcontext_t *mcp, int flags)
 	get_fpcontext(td, mcp);
 	mcp->mc_fsbase = pcb->pcb_fsbase;
 	mcp->mc_gsbase = pcb->pcb_gsbase;
+	bzero(mcp->mc_spare, sizeof(mcp->mc_spare));
 	return (0);
 }
 
diff --git a/sys/amd64/ia32/ia32_signal.c b/sys/amd64/ia32/ia32_signal.c
index e5f82fe..29dd01f 100644
--- a/sys/amd64/ia32/ia32_signal.c
+++ b/sys/amd64/ia32/ia32_signal.c
@@ -167,6 +167,8 @@ ia32_get_mcontext(struct thread *td, struct ia32_mcontext *mcp, int flags)
 	ia32_get_fpcontext(td, mcp);
 	mcp->mc_fsbase = pcb->pcb_fsbase;
 	mcp->mc_gsbase = pcb->pcb_gsbase;
+	bzero(mcp->mc_spare1, sizeof(mcp->mc_spare1));
+	bzero(mcp->mc_spare2, sizeof(mcp->mc_spare2));
 	set_pcb_flags(pcb, PCB_FULL_IRET);
 	return (0);
 }
@@ -233,6 +235,7 @@ freebsd32_getcontext(struct thread *td, struct freebsd32_getcontext_args *uap)
 		PROC_LOCK(td->td_proc);
 		uc.uc_sigmask = td->td_sigmask;
 		PROC_UNLOCK(td->td_proc);
+		bzero(&uc.__spare__, sizeof(uc.__spare__));
 		ret = copyout(&uc, uap->ucp, UC_COPY_SIZE);
 	}
 	return (ret);
@@ -348,6 +351,11 @@ freebsd4_ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	sf.sf_uc.uc_mcontext.mc_es = regs->tf_es;
 	sf.sf_uc.uc_mcontext.mc_fs = regs->tf_fs;
 	sf.sf_uc.uc_mcontext.mc_gs = regs->tf_gs;
+	bzero(sf.sf_uc.uc_mcontext.mc_fpregs,
+	    sizeof(sf.sf_uc.uc_mcontext.mc_fpregs));
+	bzero(sf.sf_uc.uc_mcontext.__spare__,
+	    sizeof(sf.sf_uc.uc_mcontext.__spare__));
+	bzero(sf.sf_uc.__spare__, sizeof(sf.sf_uc.__spare__));
 
 	/* Allocate space for the signal handler context. */
 	if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
@@ -365,6 +373,7 @@ freebsd4_ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	/* Build the argument list for the signal handler. */
 	sf.sf_signum = sig;
 	sf.sf_ucontext = (register_t)&sfp->sf_uc;
+	bzero(&sf.sf_si, sizeof(sf.sf_si));
 	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
 		/* Signal handler installed with SA_SIGINFO. */
 		sf.sf_siginfo = (u_int32_t)(uintptr_t)&sfp->sf_si;
@@ -468,6 +477,7 @@ ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	fpstate_drop(td);
 	sf.sf_uc.uc_mcontext.mc_fsbase = td->td_pcb->pcb_fsbase;
 	sf.sf_uc.uc_mcontext.mc_gsbase = td->td_pcb->pcb_gsbase;
+	bzero(sf.sf_uc.__spare__, sizeof(sf.sf_uc.__spare__));
 
 	/* Allocate space for the signal handler context. */
 	if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
@@ -487,6 +497,7 @@ ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	/* Build the argument list for the signal handler. */
 	sf.sf_signum = sig;
 	sf.sf_ucontext = (register_t)&sfp->sf_uc;
+	bzero(&sf.sf_si, sizeof(sf.sf_si));
 	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
 		/* Signal handler installed with SA_SIGINFO. */
 		sf.sf_siginfo = (u_int32_t)(uintptr_t)&sfp->sf_si;
diff --git a/sys/i386/i386/machdep.c b/sys/i386/i386/machdep.c
index 1e7013d..3768bcd 100644
--- a/sys/i386/i386/machdep.c
+++ b/sys/i386/i386/machdep.c
@@ -376,12 +376,14 @@ osendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	/* Build the argument list for the signal handler. */
 	sf.sf_signum = sig;
 	sf.sf_scp = (register_t)&fp->sf_siginfo.si_sc;
+	bzero(&sf.sf_siginfo, sizeof(sf.sf_siginfo));
 	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
 		/* Signal handler installed with SA_SIGINFO. */
 		sf.sf_arg2 = (register_t)&fp->sf_siginfo;
 		sf.sf_siginfo.si_signo = sig;
 		sf.sf_siginfo.si_code = ksi->ksi_code;
 		sf.sf_ahu.sf_action = (__osiginfohandler_t *)catcher;
+		sf.sf_addr = 0;
 	} else {
 		/* Old FreeBSD-style arguments. */
 		sf.sf_arg2 = ksi->ksi_code;
@@ -495,6 +497,11 @@ freebsd4_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	sf.sf_uc.uc_mcontext.mc_onstack = (oonstack) ? 1 : 0;
 	sf.sf_uc.uc_mcontext.mc_gs = rgs();
 	bcopy(regs, &sf.sf_uc.uc_mcontext.mc_fs, sizeof(*regs));
+	bzero(sf.sf_uc.uc_mcontext.mc_fpregs,
+	    sizeof(sf.sf_uc.uc_mcontext.mc_fpregs));
+	bzero(sf.sf_uc.uc_mcontext.__spare__,
+	    sizeof(sf.sf_uc.uc_mcontext.__spare__));
+	bzero(sf.sf_uc.__spare__, sizeof(sf.sf_uc.__spare__));
 
 	/* Allocate space for the signal handler context. */
 	if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
@@ -514,6 +521,7 @@ freebsd4_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	/* Build the argument list for the signal handler. */
 	sf.sf_signum = sig;
 	sf.sf_ucontext = (register_t)&sfp->sf_uc;
+	bzero(&sf.sf_si, sizeof(sf.sf_si));
 	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
 		/* Signal handler installed with SA_SIGINFO. */
 		sf.sf_siginfo = (register_t)&sfp->sf_si;
@@ -640,6 +648,11 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	sdp = &td->td_pcb->pcb_gsd;
 	sf.sf_uc.uc_mcontext.mc_gsbase = sdp->sd_hibase << 24 |
 	    sdp->sd_lobase;
+	bzero(sf.sf_uc.uc_mcontext.mc_spare1,
+	    sizeof(sf.sf_uc.uc_mcontext.mc_spare1));
+	bzero(sf.sf_uc.uc_mcontext.mc_spare2,
+	    sizeof(sf.sf_uc.uc_mcontext.mc_spare2));
+	bzero(sf.sf_uc.__spare__, sizeof(sf.sf_uc.__spare__));
 
 	/* Allocate space for the signal handler context. */
 	if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
@@ -661,6 +674,7 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	/* Build the argument list for the signal handler. */
 	sf.sf_signum = sig;
 	sf.sf_ucontext = (register_t)&sfp->sf_uc;
+	bzero(&sf.sf_si, sizeof(sf.sf_si));
 	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
 		/* Signal handler installed with SA_SIGINFO. */
 		sf.sf_siginfo = (register_t)&sfp->sf_si;
@@ -3286,7 +3300,8 @@ get_mcontext(struct thread *td, mcontext_t *mcp, int flags)
 	mcp->mc_fsbase = sdp->sd_hibase << 24 | sdp->sd_lobase;
 	sdp = &td->td_pcb->pcb_gsd;
 	mcp->mc_gsbase = sdp->sd_hibase << 24 | sdp->sd_lobase;
-
+	bzero(mcp->mc_spare1, sizeof(mcp->mc_spare1));
+	bzero(mcp->mc_spare2, sizeof(mcp->mc_spare2));
 	return (0);
 }
 
@@ -3335,6 +3350,7 @@ get_fpcontext(struct thread *td, mcontext_t *mcp)
 #ifndef DEV_NPX
 	mcp->mc_fpformat = _MC_FPFMT_NODEV;
 	mcp->mc_ownedfp = _MC_FPOWNED_NONE;
+	bzero(mcp->mc_fpstate, sizeof(mcp->mc_fpstate));
 #else
 	mcp->mc_ownedfp = npxgetregs(td);
 	bcopy(&td->td_pcb->pcb_user_save, &mcp->mc_fpstate,
diff --git a/sys/kern/kern_context.c b/sys/kern/kern_context.c
index 4424eff..9230857 100644
--- a/sys/kern/kern_context.c
+++ b/sys/kern/kern_context.c
@@ -72,6 +72,7 @@ getcontext(struct thread *td, struct getcontext_args *uap)
 		PROC_LOCK(td->td_proc);
 		uc.uc_sigmask = td->td_sigmask;
 		PROC_UNLOCK(td->td_proc);
+		bzero(uc.__spare__, sizeof(uc.__spare__));
 		ret = copyout(&uc, uap->ucp, UC_COPY_SIZE);
 	}
 	return (ret);
@@ -108,6 +109,7 @@ swapcontext(struct thread *td, struct swapcontext_args *uap)
 		ret = EINVAL;
 	else {
 		get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
+		bzero(uc.__spare__, sizeof(uc.__spare__));
 		PROC_LOCK(td->td_proc);
 		uc.uc_sigmask = td->td_sigmask;
 		PROC_UNLOCK(td->td_proc);