Date: Wed, 30 May 2018 03:48:28 +0000 (UTC) From: Justin Hibbits <jhibbits@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r334370 - head/sys/cddl/dev/dtrace/powerpc Message-ID: <201805300348.w4U3mSKM066084@repo.freebsd.org>
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Author: jhibbits Date: Wed May 30 03:48:27 2018 New Revision: 334370 URL: https://svnweb.freebsd.org/changeset/base/334370 Log: Protect dtrace_getpcstack() from a NULL stack pointer in a trap frame Found when trying to use lockstat on a POWER9, the stack pointer (r1) could be NULL, and result in a NULL pointer dereference, crashing the kernel. Modified: head/sys/cddl/dev/dtrace/powerpc/dtrace_isa.c Modified: head/sys/cddl/dev/dtrace/powerpc/dtrace_isa.c ============================================================================== --- head/sys/cddl/dev/dtrace/powerpc/dtrace_isa.c Wed May 30 03:40:02 2018 (r334369) +++ head/sys/cddl/dev/dtrace/powerpc/dtrace_isa.c Wed May 30 03:48:27 2018 (r334370) @@ -98,6 +98,7 @@ static __inline uintptr_t dtrace_next_sp(uintptr_t sp) { vm_offset_t callpc; + uintptr_t *r1; struct trapframe *frame; #ifdef __powerpc64__ @@ -114,7 +115,10 @@ dtrace_next_sp(uintptr_t sp) callpc + OFFSET == (vm_offset_t) &asttrapexit)) { /* Access the trap frame */ frame = (struct trapframe *)(sp + FRAME_OFFSET); - return (*(uintptr_t *)(frame->fixreg[1])); + r1 = (uintptr_t *)frame->fixreg[1]; + if (r1 == NULL) + return (0); + return (*r1); } return (*(uintptr_t*)sp);
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