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In sys___sigreturn14(), validate the saved branch target registers and

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program counter to avoid a possible kernel-mode IADDERR exception when
we try to restore the trapframe on return to user-mode.
This commit is contained in:
scw 2002-07-11 14:15:32 +00:00
parent 384b76c19b
commit 5c90e3c0d6
1 changed files with 23 additions and 1 deletions
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24
sys/arch/sh5/sh5/sig_machdep.c
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@ -1,4 +1,4 @@
/* $NetBSD: sig_machdep.c,v 1.3 2002/07/10 15:55:02 scw Exp $ */
/* $NetBSD: sig_machdep.c,v 1.4 2002/07/11 14:15:32 scw Exp $ */
/*
* Copyright 2002 Wasabi Systems, Inc.
@ -128,6 +128,7 @@ sendsig(int sig, sigset_t *returnmask, u_long code)
tf->tf_state.sf_spc = (register_t)(uintptr_t)catcher;
tf->tf_caller.r2 = sig;
tf->tf_caller.r3 = code;
tf->tf_caller.r4 = (register_t)(uintptr_t)scp;
tf->tf_caller.r15 = (register_t)(uintptr_t)scp;
/* Remember that we're now on the signal stack. */
@ -153,6 +154,8 @@ sys___sigreturn14(struct proc *p, void *v, register_t *retval)
} */ *uap = v;
struct sigcontext *scp, ksc;
struct trapframe *tf;
register_t effmask;
int i;
tf = p->p_md.md_regs;
@ -171,6 +174,25 @@ sys___sigreturn14(struct proc *p, void *v, register_t *retval)
if (ksc.sc_regs.r_intregs[24] != 0xACEBABE5ULL) /* magic number */
return (EINVAL);
/*
* Validate the branch target registers. If don't, we risk
* a kernel-mode exception when trying to restore invalid
* values to them just before returning to user-mode.
*/
effmask = ~((1ULL << SH5_NEFF_BITS) - 1);
for (i = 0; i < 8; i++) {
if ((llabs(ksc.sc_regs.r_tr[i]) & effmask) != 0 ||
(ksc.sc_regs.r_tr[i] & 0x3) == 0x3)
return (EINVAL);
}
/*
* Ditto for the PC
*/
if ((llabs(ksc.sc_regs.r_pc) & effmask) != 0 ||
(ksc.sc_regs.r_pc & 0x3) == 0x3)
return (EINVAL);
/* Restore register context. */
process_write_regs(p, &ksc.sc_regs);
if ((ksc.sc_fpstate & MDP_FPSAVED) != 0) {