[Mono-bugs] [Bug 391125] New: invalid reads in jit-info-table code

bugzilla_noreply at novell.com bugzilla_noreply at novell.com
Thu May 15 21:12:45 EDT 2008


           Summary: invalid reads in jit-info-table code
           Product: Mono: Runtime
           Version: SVN
          Platform: Other
        OS/Version: Other
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: misc
        AssignedTo: mprobst at novell.com
        ReportedBy: vargaz at gmail.com
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---

To reproduce:
- apply the following patch to driver.c:
Index: driver.c
--- driver.c    (revision 103148)
+++ driver.c    (working copy)
@@ -475,6 +475,8 @@
        return total;

 typedef struct _JitInfoData
@@ -621,7 +623,7 @@
                while (free->next != NULL) {
                        JitInfoData *next = free->next->next;

-                       g_free (free->next->ji);
+                       //g_free (free->next->ji);
                        g_free (free->next);
                        free->next = next;

@@ -707,6 +709,9 @@

                                (*data)->ji->cas_inited = 0; /* marks a free
jit info */

+                               g_free ((*data)->ji);
                                free = *data;
                                *data = (*data)->next;

- Run mono --test-jit-info-table foo.exe

-> random crash.

I think the problem here is that when the table is replaced in
mono_jit_info_table_add (), the old table is saved somewhere by the hazard
pointer code, then traversed later by jit_info_table_free (). By that time
however, some entries in the table might point to already freed MonoJitInfo
structures, and the code might mistake them for tombstones, freeing them 
again. A solution could be adding a separate 'freed' bitmap to each chunk.

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