commit 58d9ce4730d95103c9388be264a170ab852432a9

Author: mjw <mjw@a5019735-40e9-0310-863c-91ae7b9d1cf9>

Date:   Thu Apr 11 17:55:39 2013 +0000

    read_unitinfo_dwarf2 DW_FORM_ref_addr is address size in DWARF version 2.

    Bug #305513 contained a patch for some extra robustness checks. But

    the real cause of crashing in the read_unitinfo_dwarf2 DWARF reader

    seemed to have been this issue where DWARF version 2 DWZ partial_units

    were read and DW_FORM_ref_addr had an unexpected size. This combination

    is rare. DWARF version 4 is the current default version of GCC.

    git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13367 a5019735-40e9-0310-863c-91ae7b9d1cf9

diff --git a/coregrind/m_debuginfo/readdwarf.c b/coregrind/m_debuginfo/readdwarf.c

index ce34bc7..52a9099 100644

--- a/coregrind/m_debuginfo/readdwarf.c

+++ b/coregrind/m_debuginfo/readdwarf.c

@@ -991,7 +991,7 @@ void read_unitinfo_dwarf2( /*OUT*/UnitInfo* ui,

    UInt   acode, abcode;

    ULong  atoffs, blklen;

    Int    level;

-   /* UShort ver; */

+   UShort ver;

    UChar addr_size;

    UChar* p = unitblock_img;

@@ -1008,7 +1008,7 @@ void read_unitinfo_dwarf2( /*OUT*/UnitInfo* ui,

    p += ui->dw64 ? 12 : 4;

    /* version should be 2, 3 or 4 */

-   /* ver = ML_(read_UShort)(p); */

+   ver = ML_(read_UShort)(p);

    p += 2;

    /* get offset in abbrev */

@@ -1122,7 +1122,7 @@ void read_unitinfo_dwarf2( /*OUT*/UnitInfo* ui,

             case 0x0c: /* FORM_flag */      p++; break;

             case 0x0d: /* FORM_sdata */     read_leb128S( &p ); break;

             case 0x0f: /* FORM_udata */     read_leb128U( &p ); break;

-            case 0x10: /* FORM_ref_addr */  p += ui->dw64 ? 8 : 4; break;

+            case 0x10: /* FORM_ref_addr */  p += (ver == 2) ? addr_size : (ui->dw64 ? 8 : 4); break;

             case 0x11: /* FORM_ref1 */      p++; break;

             case 0x12: /* FORM_ref2 */      p += 2; break;

             case 0x13: /* FORM_ref4 */      p += 4; break;

commit 4c3b2379fb2cb97f762617df7770b042b1f8a59c

Author: mjw <mjw@a5019735-40e9-0310-863c-91ae7b9d1cf9>

Date:   Wed Apr 17 13:48:29 2013 +0000

    Simplify read_unitinfo_dwarf2. Only try to read the first DIE.

    Bug #305513. We should only read the first DIE of a compilation unit.

    Each compilation unit header is followed by a single DW_TAG_compile_unit

    (or DW_TAG_partial_unit, but those aren't important here) and its children.

    There is no reason to read any of the children at this point. If the first

    DIE isn't a DW_TAG_compile_unit we are done, none of the child DIEs will

    provide any useful information.

    git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13369 a5019735-40e9-0310-863c-91ae7b9d1cf9

diff --git a/coregrind/m_debuginfo/readdwarf.c b/coregrind/m_debuginfo/readdwarf.c

index 52a9099..764295c 100644

--- a/coregrind/m_debuginfo/readdwarf.c

+++ b/coregrind/m_debuginfo/readdwarf.c

@@ -965,12 +965,14 @@ static UChar* lookup_abbrev( UChar* p, UInt acode )

 }

 /* Read general information for a particular compile unit block in

- * the .debug_info section.

+ * the .debug_info section. In particular read the name, compdir and

+ * stmt_list needed to parse the line number information.

  * 

  * Input: - unitblock is the start of a compilation

  *          unit block in .debuginfo section

  *        - debugabbrev is start of .debug_abbrev section

  *        - debugstr is start of .debug_str section

+ *        - debugstr_alt_img is start of .debug_str section in alt debug file

  *        

  * Output: Fill members of ui pertaining to the compilation unit:

  *         - ui->name is the name of the compilation unit

@@ -990,7 +992,6 @@ void read_unitinfo_dwarf2( /*OUT*/UnitInfo* ui,

 {

    UInt   acode, abcode;

    ULong  atoffs, blklen;

-   Int    level;

    UShort ver;

    UChar addr_size;

@@ -1021,39 +1022,32 @@ void read_unitinfo_dwarf2( /*OUT*/UnitInfo* ui,

    end_img     = unitblock_img 

                  + blklen + (ui->dw64 ? 12 : 4); /* End of this block */

-   level       = 0;                        /* Level in the abbrev tree */

    abbrev_img  = debugabbrev_img 

                  + atoffs; /* Abbreviation data for this block */

-   /* Read the compilation unit entries */

-   while ( p < end_img ) {

-      Bool has_child;

+   /* Read the compilation unit entry - this is always the first DIE.

+    * See DWARF4 para 7.5. */

+   if ( p < end_img ) {

       UInt tag;

       acode = read_leb128U( &p ); /* abbreviation code */

-      if ( acode == 0 ) {

-         /* NULL entry used for padding - or last child for a sequence

-            - see para 7.5.3 */

-         level--;

-         continue;

-      }

       /* Read abbreviation header */

       abcode = read_leb128U( &abbrev_img ); /* abbreviation code */

       if ( acode != abcode ) {

-         /* We are in in children list, and must rewind to a

-          * previously declared abbrev code.  This code works but is

-          * not triggered since we shortcut the parsing once we have

-          * read the compile_unit block.  This should only occur when

-          * level > 0 */

+         /* This isn't illegal, but somewhat unlikely. Normally the

+          * first abbrev describes the first DIE, the compile_unit.

+          * But maybe this abbrevation data is shared with another

+          * or it is a NULL entry used for padding. See para 7.5.3. */

          abbrev_img = lookup_abbrev( debugabbrev_img + atoffs, acode );

       }

       tag = read_leb128U( &abbrev_img );

-      has_child = *(abbrev_img++) == 1; /* DW_CHILDREN_yes */

-      if ( has_child )

-         level++;

+      if ( tag != 0x0011 /*TAG_compile_unit*/ )

+         return; /* Not a compile unit (might be partial) or broken DWARF. */

+

+      abbrev_img++; /* DW_CHILDREN_yes or DW_CHILDREN_no */

       /* And loop on entries */

       for ( ; ; ) {

@@ -1151,16 +1145,9 @@ void read_unitinfo_dwarf2( /*OUT*/UnitInfo* ui,

             else if ( name == 0x10 ) ui->stmt_list = cval; /* DW_AT_stmt_list */

          }

       }

-      /* Shortcut the parsing once we have read the compile_unit block

-       * That's enough info for us, and we are not gdb ! */

-      if ( tag == 0x0011 /*TAG_compile_unit*/ )

-         break;

-   } /* Loop on each sub block */

-

-   /* This test would be valid if we were not shortcutting the parsing

-   if (level != 0)

-      VG_(printf)( "#### Exiting debuginfo block at level %d !!!\n", level );

-   */

+   } /* Just read the first DIE, if that wasn't the compile_unit then

+      * this might have been a partial unit or broken DWARF info.

+      * That's enough info for us, and we are not gdb ! */

 }