From 800da341bc4a35f4b4d82d104b130825d9a42ffa Mon Sep 17 00:00:00 2001 From: Mark Johnston Date: Mon, 22 Apr 2024 11:43:17 -0400 Subject: [PATCH] thread: Simplify sanitizer integration with thread creation fork() may allocate a new thread in one of two ways: from UMA, or cached in a freed proc that was just allocated from UMA. In either case, KASAN and KMSAN need to initialize some state; in particular they need to initialize the shadow mapping of the new thread's stack. This is done differently between KASAN and KMSAN, which is confusing. This patch improves things a bit: - Add a new thread_recycle() function, which moves all kernel stack handling out of kern_fork.c, since it doesn't really belong there. - Then, thread_alloc_stack() has only one local caller, so just inline it. - Avoid redundant shadow stack initialization: thread_alloc() initializes the KMSAN shadow stack (via kmsan_thread_alloc()) even through vm_thread_new() already did that. - Add kasan_thread_alloc(), for consistency with kmsan_thread_alloc(). No functional change intended. Reviewed by: khng MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D44891 --- sys/kern/kern_fork.c | 17 +++-------------- sys/kern/kern_thread.c | 20 ++++++++++++-------- sys/kern/subr_asan.c | 10 ++++++++++ sys/sys/asan.h | 4 ++++ sys/sys/proc.h | 2 +- sys/vm/vm_glue.c | 9 ++++----- 6 files changed, 34 insertions(+), 28 deletions(-) diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c index d0044dfc19a..41f6a76c4fa 100644 --- a/sys/kern/kern_fork.c +++ b/sys/kern/kern_fork.c @@ -40,7 +40,6 @@ #include #include -#include #include #include #include @@ -1019,19 +1018,9 @@ fork1(struct thread *td, struct fork_req *fr) } proc_linkup(newproc, td2); } else { - kmsan_thread_alloc(td2); - if (td2->td_kstack == 0 || td2->td_kstack_pages != pages) { - if (td2->td_kstack != 0) - vm_thread_dispose(td2); - if (!thread_alloc_stack(td2, pages)) { - error = ENOMEM; - goto fail2; - } - } else { - kasan_mark((void *)td2->td_kstack, - ptoa(td2->td_kstack_pages), - ptoa(td2->td_kstack_pages), 0); - } + error = thread_recycle(td2, pages); + if (error != 0) + goto fail2; } if ((flags & RFMEM) == 0) { diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c index 0bcd5c2f2ad..725791769ac 100644 --- a/sys/kern/kern_thread.c +++ b/sys/kern/kern_thread.c @@ -798,6 +798,7 @@ thread_alloc(int pages) } td->td_tid = tid; bzero(&td->td_sa.args, sizeof(td->td_sa.args)); + kasan_thread_alloc(td); kmsan_thread_alloc(td); cpu_thread_alloc(td); EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td); @@ -805,15 +806,18 @@ thread_alloc(int pages) } int -thread_alloc_stack(struct thread *td, int pages) +thread_recycle(struct thread *td, int pages) { - - KASSERT(td->td_kstack == 0, - ("thread_alloc_stack called on a thread with kstack")); - if (!vm_thread_new(td, pages)) - return (0); - cpu_thread_alloc(td); - return (1); + if (td->td_kstack == 0 || td->td_kstack_pages != pages) { + if (td->td_kstack != 0) + vm_thread_dispose(td); + if (!vm_thread_new(td, pages)) + return (ENOMEM); + cpu_thread_alloc(td); + } + kasan_thread_alloc(td); + kmsan_thread_alloc(td); + return (0); } /* diff --git a/sys/kern/subr_asan.c b/sys/kern/subr_asan.c index c3664d9cf6c..75d9e75c531 100644 --- a/sys/kern/subr_asan.c +++ b/sys/kern/subr_asan.c @@ -39,6 +39,7 @@ __KERNEL_RCSID(0, "$NetBSD: subr_asan.c,v 1.26 2020/09/10 14:10:46 maxv Exp $"); #include #include #include +#include #include #include @@ -294,6 +295,15 @@ kasan_mark(const void *addr, size_t size, size_t redzsize, uint8_t code) } } +void +kasan_thread_alloc(struct thread *td) +{ + if (td->td_kstack != 0) { + kasan_mark((void *)td->td_kstack, ptoa(td->td_kstack_pages), + ptoa(td->td_kstack_pages), 0); + } +} + /* -------------------------------------------------------------------------- */ #define ADDR_CROSSES_SCALE_BOUNDARY(addr, size) \ diff --git a/sys/sys/asan.h b/sys/sys/asan.h index a3becdef5f5..6a01d053172 100644 --- a/sys/sys/asan.h +++ b/sys/sys/asan.h @@ -53,14 +53,18 @@ #define KASAN_KSTACK_FREED 0xFE #define KASAN_EXEC_ARGS_FREED 0xFF +struct thread; + void kasan_init(void); void kasan_init_early(vm_offset_t, size_t); void kasan_shadow_map(vm_offset_t, size_t); void kasan_mark(const void *, size_t, size_t, uint8_t); +void kasan_thread_alloc(struct thread *); #else /* KASAN */ #define kasan_init() #define kasan_shadow_map(a, s) #define kasan_mark(p, s, l, c) +#define kasan_thread_alloc(t) #endif /* !KASAN */ #endif /* !_SYS_ASAN_H_ */ diff --git a/sys/sys/proc.h b/sys/sys/proc.h index 33b836f4150..1b542d1374b 100644 --- a/sys/sys/proc.h +++ b/sys/sys/proc.h @@ -1262,7 +1262,6 @@ void cpu_thread_free(struct thread *); void cpu_thread_swapin(struct thread *); void cpu_thread_swapout(struct thread *); struct thread *thread_alloc(int pages); -int thread_alloc_stack(struct thread *, int pages); int thread_check_susp(struct thread *td, bool sleep); void thread_cow_get_proc(struct thread *newtd, struct proc *p); void thread_cow_get(struct thread *newtd, struct thread *td); @@ -1275,6 +1274,7 @@ void thread_exit(void) __dead2; void thread_free(struct thread *td); void thread_link(struct thread *td, struct proc *p); void thread_reap_barrier(void); +int thread_recycle(struct thread *, int pages); int thread_single(struct proc *p, int how); void thread_single_end(struct proc *p, int how); void thread_stash(struct thread *td); diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c index 4292a753350..f9235fe03fa 100644 --- a/sys/vm/vm_glue.c +++ b/sys/vm/vm_glue.c @@ -543,8 +543,6 @@ vm_thread_new(struct thread *td, int pages) td->td_kstack = ks; td->td_kstack_pages = pages; td->td_kstack_domain = ks_domain; - kasan_mark((void *)ks, ptoa(pages), ptoa(pages), 0); - kmsan_mark((void *)ks, ptoa(pages), KMSAN_STATE_UNINIT); return (1); } @@ -562,11 +560,12 @@ vm_thread_dispose(struct thread *td) td->td_kstack = 0; td->td_kstack_pages = 0; td->td_kstack_domain = MAXMEMDOM; - kasan_mark((void *)ks, 0, ptoa(pages), KASAN_KSTACK_FREED); - if (pages == kstack_pages) + if (pages == kstack_pages) { + kasan_mark((void *)ks, 0, ptoa(pages), KASAN_KSTACK_FREED); uma_zfree(kstack_cache, (void *)ks); - else + } else { vm_thread_stack_dispose(ks, pages); + } } /* -- 2.45.0