auxv: Use real size of the auxv vector

The size of vector depends on the kernel config
so use the real size of a vector dumped. Otherwise
we might fail on restore.
Reported-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-dump.c

@@ -537,7 +537,7 @@ static int dump_task_creds(struct parasite_ctl *ctl, const struct cr_fdset *fds)
 #define assign_reg(dst, src, e)		do { dst->e = (__typeof__(dst->e))src.e; } while (0)
 #define assign_array(dst, src, e)	memcpy(dst->e, &src.e, sizeof(src.e))
 
-static int get_task_auxv(pid_t pid, MmEntry *mm)
+static int get_task_auxv(pid_t pid, MmEntry *mm, size_t *size)
 {
 	int fd, ret, i;
 
@@ -560,6 +560,7 @@ static int get_task_auxv(pid_t pid, MmEntry *mm)
 		}
 	}
 
+	*size = i;
 	ret = 0;
 err:
 	close_safe(&fd);
@@ -591,7 +592,7 @@ static int dump_task_mm(pid_t pid, const struct proc_pid_stat *stat,
 	if (!mme.mm_saved_auxv)
 		goto out;
 
-	if (get_task_auxv(pid, &mme))
+	if (get_task_auxv(pid, &mme, &mme.n_mm_saved_auxv))
 		goto out;
 	pr_info("OK\n");
 

cr-restore.c

@@ -1208,13 +1208,14 @@ static int prepare_mm(pid_t pid, struct task_restore_core_args *args)
 	args->mm.n_mm_saved_auxv = 0;
 	args->mm.mm_saved_auxv = NULL;
 
-	if (mm->n_mm_saved_auxv != AT_VECTOR_SIZE) {
+	if (mm->n_mm_saved_auxv > AT_VECTOR_SIZE) {
 		pr_err("Image corrupted on pid %d\n", pid);
 		goto out;
 	}
 
+	args->mm_saved_auxv_size = pb_repeated_size(mm, mm_saved_auxv);
 	memcpy(args->mm_saved_auxv, mm->mm_saved_auxv,
-	       pb_repeated_size(mm, mm_saved_auxv));
+	       args->mm_saved_auxv_size);
 
 	exe_fd = open_reg_by_id(args->mm.exe_file_id);
 	if (exe_fd < 0)

include/restorer.h

@@ -110,6 +110,7 @@ struct task_restore_core_args {
 
 	MmEntry				mm;
 	u64				mm_saved_auxv[AT_VECTOR_SIZE];
+	u32				mm_saved_auxv_size;
 	u64				blk_sigset;
 	char				comm[TASK_COMM_LEN];
 	TaskKobjIdsEntry		ids;

restorer.c

@@ -467,8 +467,7 @@ long __export_restore_task(struct task_restore_core_args *args)
 	ret |= sys_prctl_safe(PR_SET_MM, PR_SET_MM_ARG_END,	(long)args->mm.mm_arg_end, 0);
 	ret |= sys_prctl_safe(PR_SET_MM, PR_SET_MM_ENV_START,	(long)args->mm.mm_env_start, 0);
 	ret |= sys_prctl_safe(PR_SET_MM, PR_SET_MM_ENV_END,	(long)args->mm.mm_env_end, 0);
-	ret |= sys_prctl_safe(PR_SET_MM, PR_SET_MM_AUXV,	(long)args->mm_saved_auxv,
-								sizeof(args->mm_saved_auxv));
+	ret |= sys_prctl_safe(PR_SET_MM, PR_SET_MM_AUXV,	(long)args->mm_saved_auxv, args->mm_saved_auxv_size);
 	if (ret)
 		goto core_restore_end;