Date: Fri, 11 Jan 2019 11:32:46 +0000 (UTC) From: Andrew Turner <andrew@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r342937 - head/sys/arm64/arm64 Message-ID: <201901111132.x0BBWkj2011422@repo.freebsd.org>
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Author: andrew Date: Fri Jan 11 11:32:46 2019 New Revision: 342937 URL: https://svnweb.freebsd.org/changeset/base/342937 Log: Fix the location of td->td_frame at the top of the kernel stack. In cpu_thread_alloc we would allocate space for the trap frame at the top of the kernel stack. This is just below the pcb, however due to a missing cast the pointer arithmetic would use the pcb size, not the trapframe size. As the pcb is larger than the trapframe this is safe, however later in cpu_fork we include the case leading to the two disagreeing on the location. Fix by using the same arithmetic in both locations. Found by: An early KASAN patch Sponsored by: DARPA, AFRL Modified: head/sys/arm64/arm64/vm_machdep.c Modified: head/sys/arm64/arm64/vm_machdep.c ============================================================================== --- head/sys/arm64/arm64/vm_machdep.c Fri Jan 11 09:40:34 2019 (r342936) +++ head/sys/arm64/arm64/vm_machdep.c Fri Jan 11 11:32:46 2019 (r342937) @@ -228,7 +228,7 @@ cpu_thread_alloc(struct thread *td) td->td_pcb = (struct pcb *)(td->td_kstack + td->td_kstack_pages * PAGE_SIZE) - 1; td->td_frame = (struct trapframe *)STACKALIGN( - td->td_pcb - 1); + (struct trapframe *)td->td_pcb - 1); } void
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