[Minios-devel] [UNIKRAFT PATCH] lib/ukboot: Fix handling of main arguments

[Costin Lupu <costin.lupu@xxxxxxxxx>]

When the command line is parsed and split into arguments, each argument
is saved in an array of pointers allocated on the stack ('argv' array in
ukplat_entry_argp()). This means that the array can be overwritten any
time before starting the main thread which needs the arguments. This
patch fixes that by making the array global, encapsulated by the
'main_arg' structure.

Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
---
 include/uk/plat/bootstrap.h | 11 ++++++++++-
 lib/ukboot/boot.c           | 33 ++++++++++++---------------------
 lib/ukboot/exportsyms.uk    |  1 +
 plat/linuxu/setup.c         |  7 ++++++-
 4 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/include/uk/plat/bootstrap.h b/include/uk/plat/bootstrap.h
index 0652ccd1..a9e404e8 100644
--- a/include/uk/plat/bootstrap.h
+++ b/include/uk/plat/bootstrap.h
@@ -36,6 +36,7 @@
 #ifndef __UKPLAT_BOOTSTRAP__
 #define __UKPLAT_BOOTSTRAP__
 
+#include <uk/config.h>
 #include <uk/arch/types.h>
 #include <uk/essentials.h>
 
@@ -43,6 +44,14 @@
 extern "C" {
 #endif
 
+/* Main arguments structure */
+struct main_arg {
+       int argc;
+       char *argv[CONFIG_LIBUKBOOT_MAXNBARGS];
+};
+/* Main arguments */
+extern struct main_arg global_main_arg;
+
 /**
  * Called by platform library during initialization
  * This function has to be provided by a non-platform library for bootstrapping
@@ -52,7 +61,7 @@ extern "C" {
  * @param argc Number of arguments
  * @param args Array to '\0'-terminated arguments
  */
-void ukplat_entry(int argc, char *argv[]) __noreturn;
+void ukplat_entry(struct main_arg *arg) __noreturn;
 
 /**
  * Called by platform library during initialization
diff --git a/lib/ukboot/boot.c b/lib/ukboot/boot.c
index 4dcc0afb..5cc3b573 100644
--- a/lib/ukboot/boot.c
+++ b/lib/ukboot/boot.c
@@ -68,17 +68,13 @@ extern int liblwip_init(void);
 #endif /* CONFIG_LIBLWIP */
 
 static void main_thread_func(void *arg) __noreturn;
-
-struct thread_main_arg {
-       int argc;
-       char **argv;
-};
+struct main_arg global_main_arg;
 
 static void main_thread_func(void *arg)
 {
        int i;
        int ret;
-       struct thread_main_arg *tma = arg;
+       struct main_arg *tma = arg;
 
        uk_pr_info("Pre-init table at %p - %p\n",
                   __preinit_array_start, &__preinit_array_end);
@@ -145,26 +141,26 @@ static void main_thread_func(void *arg)
 /* defined in <uk/plat.h> */
 void ukplat_entry_argp(char *arg0, char *argb, __sz argb_len)
 {
-       char *argv[CONFIG_LIBUKBOOT_MAXNBARGS];
-       int argc = 0;
+       global_main_arg.argc = 0;
 
        if (arg0) {
-               argv[0] = arg0;
-               argc += 1;
+               global_main_arg.argv[0] = arg0;
+               global_main_arg.argc += 1;
        }
        if (argb && argb_len) {
-               argc += uk_argnparse(argb, argb_len, arg0 ? &argv[1] : &argv[0],
+               global_main_arg.argc += uk_argnparse(argb, argb_len,
+                                    arg0 ? &global_main_arg.argv[1]
+                                         : &global_main_arg.argv[0],
                                     arg0 ? (CONFIG_LIBUKBOOT_MAXNBARGS - 1)
                                          : CONFIG_LIBUKBOOT_MAXNBARGS);
        }
-       ukplat_entry(argc, argv);
+       ukplat_entry(&global_main_arg);
 }
 
 /* defined in <uk/plat.h> */
-void ukplat_entry(int argc, char *argv[])
+void ukplat_entry(struct main_arg *arg)
 {
        const uk_ctor_func_t *cfn;
-       struct thread_main_arg tma;
 #if CONFIG_LIBUKALLOC
        struct uk_alloc *a = NULL;
        int rc;
@@ -234,19 +230,14 @@ void ukplat_entry(int argc, char *argv[])
        s = uk_sched_default_init(a);
        if (unlikely(!s))
                UK_CRASH("Could not initialize the scheduler\n");
-#endif
 
-       tma.argc = argc;
-       tma.argv = argv;
-
-#if CONFIG_LIBUKSCHED
-       main_thread = uk_thread_create("main", main_thread_func, &tma);
+       main_thread = uk_thread_create("main", main_thread_func, arg);
        if (unlikely(!main_thread))
                UK_CRASH("Could not create main thread\n");
        uk_sched_start(s);
 #else
        /* Enable interrupts before starting the application */
        ukplat_lcpu_enable_irq();
-       main_thread_func(&tma);
+       main_thread_func(arg);
 #endif
 }
diff --git a/lib/ukboot/exportsyms.uk b/lib/ukboot/exportsyms.uk
index 3edc6c6a..adbb84fb 100644
--- a/lib/ukboot/exportsyms.uk
+++ b/lib/ukboot/exportsyms.uk
@@ -1,3 +1,4 @@
 ukplat_entry_argp
 ukplat_entry
+global_main_arg
 main
diff --git a/plat/linuxu/setup.c b/plat/linuxu/setup.c
index 50454437..4f6f5688 100644
--- a/plat/linuxu/setup.c
+++ b/plat/linuxu/setup.c
@@ -172,6 +172,11 @@ void _liblinuxuplat_entry(int argc, char *argv[])
        argv += (ret - 1);
        argv[0] = progname;
 
+       /* Setup global arguments */
+       global_main_arg.argc = argc;
+       for (int i = 0; i < argc; i++)
+               global_main_arg.argv[i] = argv[i];
+
        /*
         * Allocate heap memory
         */
@@ -186,5 +191,5 @@ void _liblinuxuplat_entry(int argc, char *argv[])
        /*
         * Enter Unikraft
         */
-       ukplat_entry(argc, argv);
+       ukplat_entry(&global_main_arg);
 }
-- 
2.11.0


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