libdw: dwarf_formsdata should return a signed value

The function dwarf_formsdata is used for decoding signed values, but
except for the variable-length DW_FORM_sdata, it uses unsigned
primitives to decode the value. This is not a problem for 64-bit values,
but the smaller values come decoded wrong. Fix by changing to signed
primitives for decoding the fixed-length forms.

Add a test case that uses dwarf_aggregate_size to determine an array
size whose lower bound is -1, encoded using DW_FORM_data1, and upper
bound 255 with DW_FORM_data2. When the -1 is decoded wrongly, it comes
back as 255, and the array size is 1. The correct array size should be
257.

Signed-off-by: Petr Machata <pmachata@gmail.com>

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 7cfc7825b10549298d9d773be2d18813cf3f3b57..479dd42b38a1a1269138f5d66035d3fa3cb16793 100644 (file)
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,10 @@
+2018-01-14  Petr Machata  <pmachata@gmail.com>
+
+       * dwarf_formsdata.c (dwarf_formsdata):
+       <DW_FORM_data1>: Cast to signed char.
+       <DW_FORM_data2,4,8>: Use read_*sbyte_unaligned instead of
+       read_*ubyte_unaligned.
+
 2017-12-26  Mark Wielaard  <mark@klomp.org>
 
        * libdwP.h (struct Dwarf_Abbrev): Pack struct. Remove attrcnt,

diff --git a/libdw/dwarf_formsdata.c b/libdw/dwarf_formsdata.c
index e7deaee1036bf4c60e5c30d06817cfb6662c7ae1..bc2b508d8a5426cbc2658434bf938beb42493452 100644 (file)
--- a/libdw/dwarf_formsdata.c
+++ b/libdw/dwarf_formsdata.c
@@ -53,25 +53,25 @@ dwarf_formsdata (Dwarf_Attribute *attr, Dwarf_Sword *return_sval)
          __libdw_seterrno (DWARF_E_INVALID_DWARF);
          return -1;
        }
-      *return_sval = *attr->valp;
+      *return_sval = (signed char) *attr->valp;
       break;
 
     case DW_FORM_data2:
       if (datap + 2 > endp)
        goto invalid;
-      *return_sval = read_2ubyte_unaligned (attr->cu->dbg, attr->valp);
+      *return_sval = read_2sbyte_unaligned (attr->cu->dbg, attr->valp);
       break;
 
     case DW_FORM_data4:
       if (datap + 4 > endp)
        goto invalid;
-      *return_sval = read_4ubyte_unaligned (attr->cu->dbg, attr->valp);
+      *return_sval = read_4sbyte_unaligned (attr->cu->dbg, attr->valp);
       break;
 
     case DW_FORM_data8:
       if (datap + 8 > endp)
        goto invalid;
-      *return_sval = read_8ubyte_unaligned (attr->cu->dbg, attr->valp);
+      *return_sval = read_8sbyte_unaligned (attr->cu->dbg, attr->valp);
       break;
 
     case DW_FORM_sdata:

diff --git a/tests/ChangeLog b/tests/ChangeLog
index 831532b24099444acf76882c831686f0b9f114ab..758f20e6a41ca928c7281597f6d4cb09e30dc19c 100644 (file)
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -1,3 +1,9 @@
+2018-01-14  Petr Machata  <pmachata@gmail.com>
+
+       * testfile-sizes4.o.bz2: New test file.
+       * testfile-sizes4.s: New test source.
+       * run-aggregate-size.sh: Check testfile-sizes4.o v size 257.
+
 2017-12-23  Mark Wielaard  <mark@klomp.org>
 
        * backtrace-subr.sh (check_native_core): Use a lock file and try

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 64cb5bd90168934285e1cdb9f59fc1bed5d3a838..1fce4474009cc1072a09da118cdc153183099bbc 100644 (file)
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -333,7 +333,8 @@ EXTRA_DIST = run-arextract.sh run-arsymtest.sh run-ar.sh \
             run-deleted.sh run-linkmap-cut.sh linkmap-cut-lib.so.bz2 \
             linkmap-cut.bz2 linkmap-cut.core.bz2 \
             run-aggregate-size.sh testfile-sizes1.o.bz2 testfile-sizes2.o.bz2 \
-            testfile-sizes3.o.bz2 run-peel-type.sh \
+            testfile-sizes3.o.bz2 testfile-sizes4.o.bz2 testfile-sizes4.s \
+            run-peel-type.sh \
             run-readelf-A.sh testfileppc32attrs.o.bz2 \
             testfilesparc64attrs.o.bz2 testfileppc64attrs.o.bz2 \
             testfile-debug-types.bz2 \

diff --git a/tests/run-aggregate-size.sh b/tests/run-aggregate-size.sh
index 6d8aa240187c697207656bb8e279b39957ab0f60..08d57bbf2ec07b12be25a4a81541f2ec6992d58e 100755 (executable)
--- a/tests/run-aggregate-size.sh
+++ b/tests/run-aggregate-size.sh
@@ -63,7 +63,9 @@
 #
 # gcc -std=c99 -g -c -o testfile-sizes3.o sizes.c
 
-testfiles testfile-sizes1.o testfile-sizes2.o testfile-sizes3.o
+# The file testfile-size4.o is hand-crafted.
+
+testfiles testfile-sizes1.o testfile-sizes2.o testfile-sizes3.o testfile-sizes4.o
 
 testrun_compare ${abs_builddir}/aggregate_size -e testfile-sizes1.o <<\EOF
 c size 1
@@ -104,4 +106,8 @@ f size 4
 b size 4
 EOF
 
+testrun_compare ${abs_builddir}/aggregate_size -e testfile-sizes4.o <<\EOF
+v size 257
+EOF
+
 exit 0

diff --git a/tests/testfile-sizes4.o.bz2 b/tests/testfile-sizes4.o.bz2
new file mode 100644 (file)
index 0000000..046e0a2
Binary files /dev/null and b/tests/testfile-sizes4.o.bz2 differ

diff --git a/tests/testfile-sizes4.s b/tests/testfile-sizes4.s
new file mode 100644 (file)
index 0000000..a243021
--- /dev/null
+++ b/tests/testfile-sizes4.s
@@ -0,0 +1,77 @@
+        .section .debug_info
+.Lcu1_begin:
+        .4byte        .Lcu1_end - .Lcu1_start
+.Lcu1_start:
+        .2byte        4                 /* Version */
+        .4byte        .Labbrev1_begin   /* Abbrevs */
+        .byte        8                  /* Pointer size */
+        .uleb128        2               /* Abbrev (DW_TAG_compile_unit) */
+        .uleb128        3               /* Abbrev (DW_TAG_variable) */
+        .ascii        "v\0"
+        .4byte        .Llabel1 - .Lcu1_begin
+.Llabel1:
+        .uleb128        4               /* Abbrev (DW_TAG_array_type) */
+        .4byte        .Llabel2 - .Lcu1_begin
+        .uleb128        5               /* Abbrev (DW_TAG_subrange_type) */
+        .byte        -1
+        .2byte        255
+        .byte        0x0                /* Terminate children */
+.Llabel2:
+        .uleb128        6               /* Abbrev (DW_TAG_base_type) */
+        .byte        1
+        .byte        0x0                /* Terminate children */
+.Lcu1_end:
+        .section .note.gnu.build-id, "a", %note
+        .4byte        4
+        .4byte        8
+        .4byte        3
+        .ascii        "GNU\0"
+        .byte        0x01
+        .byte        0x02
+        .byte        0x03
+        .byte        0x04
+        .byte        0x05
+        .byte        0x06
+        .byte        0x07
+        .byte        0x08
+        .section .debug_abbrev
+.Labbrev1_begin:
+        .uleb128        2               /* Abbrev start */
+        .uleb128        0x11            /* DW_TAG_compile_unit */
+        .byte        1                  /* has_children */
+        .byte        0x0                /* Terminator */
+        .byte        0x0                /* Terminator */
+        .uleb128        3               /* Abbrev start */
+        .uleb128        0x34            /* DW_TAG_variable */
+        .byte        0                  /* has_children */
+        .uleb128        0x03            /* DW_AT_name */
+        .uleb128        0x08            /* DW_FORM_string */
+        .uleb128        0x49            /* DW_AT_type */
+        .uleb128        0x13            /* DW_FORM_ref4 */
+        .byte        0x0                /* Terminator */
+        .byte        0x0                /* Terminator */
+        .uleb128        4               /* Abbrev start */
+        .uleb128        0x01            /* DW_TAG_array_type */
+        .byte        1                  /* has_children */
+        .uleb128        0x49            /* DW_AT_type */
+        .uleb128        0x13            /* DW_FORM_ref4 */
+        .byte        0x0                /* Terminator */
+        .byte        0x0                /* Terminator */
+        .uleb128        5               /* Abbrev start */
+        .uleb128        0x21            /* DW_TAG_subrange_type */
+        .byte        0                  /* has_children */
+        .uleb128        0x22            /* DW_AT_lower_bound */
+        .uleb128        0x0b            /* DW_FORM_data1 */
+        .uleb128        0x2f            /* DW_AT_upper_bound */
+        .uleb128        0x05            /* DW_FORM_data2 */
+        .byte        0x0                /* Terminator */
+        .byte        0x0                /* Terminator */
+        .uleb128        6               /* Abbrev start */
+        .uleb128        0x24            /* DW_TAG_base_type */
+        .byte        0                  /* has_children */
+        .uleb128        0x0b            /* DW_AT_byte_size */
+        .uleb128        0x0b            /* DW_FORM_data1 */
+        .byte        0x0                /* Terminator */
+        .byte        0x0                /* Terminator */
+        .byte        0x0                /* Terminator */
+        .byte        0x0                /* Terminator */