Bug 512937

Summary: Invalid STT_GNU_IFUNC SHN_UNDEF symbols
Product: [Fedora] Fedora Reporter: Jakub Jelinek <jakub>
Component: binutilsAssignee: Nick Clifton <nickc>
Status: CLOSED RAWHIDE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: high    
Version: rawhideCC: drepper, hongjiu.lu, jakub, jan.kratochvil, jfrieben, nickc, nicolas.mailhot
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Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: Bug Fix
Doc Text:
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Clone Of: Environment:
Last Closed: 2009-07-22 04:37:33 EDT Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---
Bug Depends On:    
Bug Blocks: 473303    

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: