Bug 512937 - Invalid STT_GNU_IFUNC SHN_UNDEF symbols
Product: Fedora
Classification: Fedora
Component: binutils (Show other bugs)
All Linux
high Severity high
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Assigned To: Nick Clifton
Fedora Extras Quality Assurance
: 512078 (view as bug list)
Depends On:
Blocks: F12Blocker/F12FinalBlocker
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Reported: 2009-07-21 08:37 EDT by Jakub Jelinek
Modified: 2009-07-22 13:36 EDT (History)
7 users (show)

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Last Closed: 2009-07-22 04:37:33 EDT
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Tracker ID Priority Status Summary Last Updated
Sourceware 10426 None None None Never

  None (edit)
Description Jakub Jelinek 2009-07-21 08:37:11 EDT
Description of problem: ld creates STT_GNU_IFUNC SHN_UNDEF symbols.

How reproducible:

extern __SIZE_TYPE__ strlen (const char *);

foo (const char *p)
  return strlen (p);

gcc -shared -fpic -o /tmp/x.so /tmp/x.c
readelf -Ws /tmp/x.so | grep IFUNC
     4: 0000000000000000     0 IFUNC   GLOBAL DEFAULT  UND strlen@GLIBC_2.2.5 (2)
    47: 0000000000000000     0 IFUNC   GLOBAL DEFAULT  UND strlen@@GLIBC_2.2.5

Haven't checked trunk binutils.

STT_GNU_IFUNC should be used solely on symbol definitions, not when a symbol is undefined.  Whether it will bind to STT_GNU_IFUNC or normal STT_FUNC is unclear at runtime, and STT_FUNC should be used.

It would be very good if this could be fixed before the mass rebuild starts (I believe 2009-07-23).
Comment 1 Jakub Jelinek 2009-07-21 11:47:58 EDT
*** Bug 512078 has been marked as a duplicate of this bug. ***
Comment 2 Jakub Jelinek 2009-07-21 12:08:07 EDT
Here is a reproducer in the binutils tree:
gcc  -B$BINUTILS_OBJ/ld/tmpdir/gas/ -I$BINUTILS_SRC/ld/testsuite/ld-ifunc -g -O2 \
  -c -fPIC -DWITH_IFUNC -c $BINUTILS_SRC/ld/testsuite/ld-ifunc/lib.c \
  -o shared_ifunc.o
$BINUTILS_OBJ/ld/ld-new  -o libshared_ifunc.so -shared shared_ifunc.o
echo 'extern int library_func2 (void);' > test.c
echo 'int main (void) { library_func2 (); return 0; }' >> test.c
gcc -B $BINUTILS_OBJ/ld/tmpdir/ld/ -o test test.c ./libshared_ifunc.so
$BINUTILS_OBJ/binutils/readelf -Ws test | grep IFUNC.*UND
echo 'extern int library_func2 (void);' > test2.c
echo 'int (*fn) (void) = library_func2;' >> test2.c
echo 'int main (void) { fn (); return 0; }' >> test2.c
gcc -B $BINUTILS_OBJ/ld/tmpdir/ld/ -o test2 test2.c ./libshared_ifunc.so
$BINUTILS_OBJ/binutils/readelf -Ws test2 | grep IFUNC.*UND

test2 is what is fatal for gnome-panel, but both cases are wrong, no SHN_UNDEF symbols should be ever STT_GNU_IFUNC, the should be STT_FUNC instead.
Comment 3 H.J. Lu 2009-07-21 18:16:59 EDT
It is fixed in the Linux binutils
Comment 4 Ulrich Drepper 2009-07-21 18:38:48 EDT
Thanks, HJ.

NickC, please build a new RPM right away.  We need it for the mass rebuild.
Comment 5 Nick Clifton 2009-07-22 04:37:33 EDT
New RPMS should be ready: binutils-

Comment 6 H.J. Lu 2009-07-22 13:36:16 EDT
The current linker may be broken:


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