STRLCPY/criu

vdso/ia32: separate compat vdso helper

As helper unmaps 64-bit vDSO blob, it can call only raw syscalls.
Also by that reason it's code should be not instrumented with GCOV/ASAN.
Disable instrumentation by separating it into new object and filtering
gcov/asan cflags.

Fixes: #290
@avagin, it rarely reproduces, I failed to reproduce even once
(with gcov, on the same env00 test, with the same linux-next)
please, reopen #290 if you'll spot it afterward.

Reported-by: Andrei Vagin <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Signed-off-by: Andrei Vagin <[email protected]>

Dmitry Safonov committed with Andrei Vagin 7 years ago

f2504723

1 parent 164e048a

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criu/Makefile.crtools

		skipped 85 lines
86	86		obj-y += pie-util-vdso.o
87	87		obj-y += vdso.o
88	88		obj-y += pie-util-vdso-elf32.o
89		-	CFLAGS_pie-util-vdso-elf32.o += -DCONFIG_VDSO_32
	89	+	CFLAGS_pie-util-vdso-elf32.o += -DCONFIG_VDSO_32
	90	+	obj-$(CONFIG_COMPAT) += vdso-compat.o
	91	+	CFLAGS_REMOVE_vdso-compat.o += $(CFLAGS-ASAN) $(CFLAGS-GCOV)
90	92		endif
91	93
92	94		PROTOBUF_GEN := scripts/protobuf-gen.sh
		skipped 9 lines

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criu/include/vdso.h

		skipped 17 lines
18	18		extern int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
19	19		struct vm_area_list *vma_area_list);
20	20
	21	+	#ifdef CONFIG_COMPAT
	22	+	void compat_vdso_helper(struct vdso_symtable *native, int pipe_fd,
	23	+	int err_fd, void *vdso_buf, size_t buf_size);
	24	+	#endif
	25	+
21	26		#else /* CONFIG_VDSO */
22	27
23	28		#define vdso_init() (0)
		skipped 6 lines

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criu/vdso-compat.c

1	+	#include <sys/syscall.h>
2	+	#include <signal.h>
3	+	#include <string.h>
4	+	#include <unistd.h>
5	+
6	+	#include "types.h"
7	+	#include "parasite-syscall.h"
8	+	#include "parasite.h"
9	+	#include "vdso.h"
10	+
11	+	static void exit_on(int ret, int err_fd, char *reason)
12	+	{
13	+	if (ret) {
14	+	syscall(__NR_write, err_fd, reason, strlen(reason));
15	+	syscall(__NR_exit, ret);
16	+	}
17	+	}
18	+	/*
19	+	* Because of restrictions of ARCH_MAP_VDSO_* API, new vDSO blob
20	+	* can be mapped only if there is no vDSO blob present for a process.
21	+	* This is a helper process, it unmaps 64-bit vDSO and maps 32-bit vDSO.
22	+	* Then it copies vDSO blob to shared with CRIU mapping.
23	+	*
24	+	* The purpose is to fill compat vdso's symtable (vdso_compat_rt).
25	+	* It's an optimization to fill symtable only once at CRIU restore
26	+	* for all restored tasks.
27	+	*
28	+	* @native - 64-bit vDSO blob (for easy unmap)
29	+	* @pipe_fd - to get size of compat blob from /proc/.../maps
30	+	* @err_fd - to print error messages
31	+	* @vdso_buf, buf_size - shared with CRIU buffer
32	+	*
33	+	* WARN: This helper shouldn't call pr_err() or any syscall with
34	+	* Glibc's wrapper function - it may very likely blow up.
35	+	*/
36	+	void compat_vdso_helper(struct vdso_symtable *native, int pipe_fd,
37	+	int err_fd, void *vdso_buf, size_t buf_size)
38	+	{
39	+	size_t vma_size;
40	+	void *vdso_addr;
41	+	long vdso_size;
42	+	long ret;
43	+
44	+	vma_size = native->vma_end - native->vma_start;
45	+	ret = syscall(__NR_munmap, native->vma_start, vma_size);
46	+	exit_on(ret, err_fd, "Error: Failed to unmap native vdso\n");
47	+
48	+	vma_size = native->vvar_end - native->vvar_start;
49	+	ret = syscall(__NR_munmap, native->vvar_start, vma_size);
50	+	exit_on(ret, err_fd, "Error: Failed to unmap native vvar\n");
51	+
52	+	ret = syscall(__NR_arch_prctl, ARCH_MAP_VDSO_32, native->vma_start);
53	+	if (ret < 0)
54	+	exit_on(ret, err_fd, "Error: ARCH_MAP_VDSO failed\n");
55	+
56	+	vdso_size = ret;
57	+	if (vdso_size > buf_size)
58	+	exit_on(-1, err_fd, "Error: Compatible vdso's size is bigger than reserved buf\n");
59	+
60	+	/* Stop so CRIU could parse smaps to find 32-bit vdso's size */
61	+	ret = syscall(__NR_kill, syscall(__NR_getpid), SIGSTOP);
62	+	exit_on(ret, err_fd, "Error: Can't stop myself with SIGSTOP (having a good time)\n");
63	+
64	+	ret = syscall(__NR_read, pipe_fd, &vdso_addr, sizeof(void *));
65	+	if (ret != sizeof(void *))
66	+	exit_on(-1, err_fd, "Error: Can't read size of mmaped vdso from pipe\n");
67	+
68	+	memcpy(vdso_buf, vdso_addr, vdso_size);
69	+
70	+	syscall(__NR_exit, 0);
71	+	}
72	+

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criu/vdso.c

		skipped 329 lines
330	330		}
331	331
332	332		#ifdef CONFIG_COMPAT
333		-	static void exit_on(int ret, int err_fd, char *reason)
334		-	{
335		-	if (ret) {
336		-	syscall(__NR_write, err_fd, reason, strlen(reason));
337		-	syscall(__NR_exit, ret);
338		-	}
339		-	}
340		-	/*
341		-	* Because of restrictions of ARCH_MAP_VDSO_* API, new vDSO blob
342		-	* can be mapped only if there is no vDSO blob present for a process.
343		-	* This is a helper process, it unmaps 64-bit vDSO and maps 32-bit vDSO.
344		-	* Then it copies vDSO blob to shared with CRIU mapping.
345		-	*
346		-	* The purpose is to fill compat vdso's symtable (vdso_compat_rt).
347		-	* It's an optimization to fill symtable only once at CRIU restore
348		-	* for all restored tasks.
349		-	*
350		-	* @native - 64-bit vDSO blob (for easy unmap)
351		-	* @pipe_fd - to get size of compat blob from /proc/.../maps
352		-	* @err_fd - to print error messages
353		-	* @vdso_buf, buf_size - shared with CRIU buffer
354		-	*
355		-	* WARN: This helper shouldn't call pr_err() or any syscall with
356		-	* Glibc's wrapper function - it may very likely blow up.
357		-	*/
358		-	static void compat_vdso_helper(struct vdso_symtable *native, int pipe_fd,
359		-	int err_fd, void *vdso_buf, size_t buf_size)
360		-	{
361		-	size_t vma_size;
362		-	void *vdso_addr;
363		-	long vdso_size;
364		-	long ret;
365		-
366		-	vma_size = native->vma_end - native->vma_start;
367		-	ret = syscall(__NR_munmap, native->vma_start, vma_size);
368		-	exit_on(ret, err_fd, "Error: Failed to unmap native vdso\n");
369		-
370		-	vma_size = native->vvar_end - native->vvar_start;
371		-	ret = syscall(__NR_munmap, native->vvar_start, vma_size);
372		-	exit_on(ret, err_fd, "Error: Failed to unmap native vvar\n");
373		-
374		-	ret = syscall(__NR_arch_prctl, ARCH_MAP_VDSO_32, native->vma_start);
375		-	if (ret < 0)
376		-	exit_on(ret, err_fd, "Error: ARCH_MAP_VDSO failed\n");
377		-
378		-	vdso_size = ret;
379		-	if (vdso_size > buf_size)
380		-	exit_on(-1, err_fd, "Error: Compatible vdso's size is bigger than reserved buf\n");
381		-
382		-	/* Stop so CRIU could parse smaps to find 32-bit vdso's size */
383		-	ret = syscall(__NR_kill, syscall(__NR_getpid), SIGSTOP);
384		-	exit_on(ret, err_fd, "Error: Can't stop myself with SIGSTOP (having a good time)\n");
385		-
386		-	ret = syscall(__NR_read, pipe_fd, &vdso_addr, sizeof(void *));
387		-	if (ret != sizeof(void *))
388		-	exit_on(-1, err_fd, "Error: Can't read size of mmaped vdso from pipe\n");
389		-
390		-	memcpy(vdso_buf, vdso_addr, vdso_size);
391		-
392		-	syscall(__NR_exit, 0);
393		-	}
394		-
395	333		static int vdso_mmap_compat(struct vdso_symtable *native,
396	334		struct vdso_symtable compat, void vdso_buf, size_t buf_size)
397	335		{
		skipped 105 lines
503	441		return ret;
504	442		}
505	443
506		-	#else
	444	+	#else /* CONFIG_COMPAT */
507	445		static int vdso_fill_compat_symtable(struct vdso_symtable *native,
508	446		struct vdso_symtable *compat)
509	447		{
510	448		return 0;
511	449		}
512		-	#endif
	450	+	#endif /* CONFIG_COMPAT */
513	451
514	452		int vdso_init(void)
515	453		{
		skipped 18 lines