[yocto] [prelink-cross][PATCH] rtld: get machine from undef_map for protected symbols

[Mark Hatle]

On 9/28/18 9:55 AM, Kyle Russell wrote:
> Avoids rtld segfault when _dl_lookup_symbol_x is called with NULL
> for skip_map on a protected symbol relocation.
> 
> Global protected symbols may not actually require a copy relocaton,
> in which case skip_map is undefined, so use the undef_map to determine
> the symbol arch.

Thank you.  Any objections with me adding a 'Signed-off-by: ' line with your name?

I'm going to start enforcing submissions need a signed-off-by line per the terms
of the "Developer's Certificate of Origin",

https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin

(While it is not yet a requirement, I'd like to start doing it now.)

Thanks!
--Mark

> ---
>  src/rtld/dl-lookupX.h   |  6 +++---
>  testsuite/Makefile.am   |  2 +-
>  testsuite/reloc12.c     | 19 +++++++++++++++++++
>  testsuite/reloc12.h     | 11 +++++++++++
>  testsuite/reloc12.sh    | 20 ++++++++++++++++++++
>  testsuite/reloc12lib1.c | 11 +++++++++++
>  testsuite/reloc12lib2.c | 16 ++++++++++++++++
>  7 files changed, 81 insertions(+), 4 deletions(-)
>  create mode 100644 testsuite/reloc12.c
>  create mode 100644 testsuite/reloc12.h
>  create mode 100755 testsuite/reloc12.sh
>  create mode 100644 testsuite/reloc12lib1.c
>  create mode 100644 testsuite/reloc12lib2.c
> 
> diff --git a/src/rtld/dl-lookupX.h b/src/rtld/dl-lookupX.h
> index 425bb4b..250c509 100644
> --- a/src/rtld/dl-lookupX.h
> +++ b/src/rtld/dl-lookupX.h
> @@ -679,10 +679,10 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
>  	    if (do_lookup_x (undef_name, new_hash, &old_hash, *ref,
>  			     &protected_value, *scope, i, version, flags,
>  			     skip_map,
> -			     (ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA(skip_map->machine)
> +			     (ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA(undef_map->machine)
>  			      && ELFW(ST_TYPE) ((*ref)->st_info) == STT_OBJECT
> -			      && type_class == ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA(skip_map->machine))
> -			     ? ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA(skip_map->machine)
> +			      && type_class == ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA(undef_map->machine))
> +			     ? ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA(undef_map->machine)
>  			     : ELF_RTYPE_CLASS_PLT, NULL) != 0)
>  	      break;
>  
> diff --git a/testsuite/Makefile.am b/testsuite/Makefile.am
> index 030f65b..21de6a9 100644
> --- a/testsuite/Makefile.am
> +++ b/testsuite/Makefile.am
> @@ -5,7 +5,7 @@ AM_CFLAGS = -Wall
>  
>  TESTS = movelibs.sh \
>  	reloc1.sh reloc2.sh reloc3.sh reloc4.sh reloc5.sh reloc6.sh \
> -	reloc7.sh reloc8.sh reloc9.sh reloc10.sh reloc11.sh \
> +	reloc7.sh reloc8.sh reloc9.sh reloc10.sh reloc11.sh reloc12.sh \
>  	shuffle1.sh shuffle2.sh shuffle3.sh shuffle4.sh shuffle5.sh \
>  	shuffle6.sh shuffle7.sh shuffle8.sh shuffle9.sh undo1.sh \
>  	layout1.sh layout2.sh unprel1.sh \
> diff --git a/testsuite/reloc12.c b/testsuite/reloc12.c
> new file mode 100644
> index 0000000..cfa8888
> --- /dev/null
> +++ b/testsuite/reloc12.c
> @@ -0,0 +1,19 @@
> +#include "reloc12.h"
> +#include <stdlib.h>
> +
> +int main()
> +{
> +  A* ptr = find('b');
> +  if(b(ptr) != 0)
> +    abort();
> +
> +  ptr = find('a');
> +  if(b(ptr) != 1)
> +    abort();
> +
> +  ptr = find('r');
> +  if(b(ptr) != 2)
> +    abort();
> +
> +  exit(0);
> +}
> diff --git a/testsuite/reloc12.h b/testsuite/reloc12.h
> new file mode 100644
> index 0000000..8e09405
> --- /dev/null
> +++ b/testsuite/reloc12.h
> @@ -0,0 +1,11 @@
> +typedef struct
> +  {
> +    char a;
> +    int b;
> +  } A;
> +
> +extern A foo[] __attribute ((visibility ("protected")));
> +
> +A* find(char a);
> +char a(const A*);
> +int b(const A*);
> diff --git a/testsuite/reloc12.sh b/testsuite/reloc12.sh
> new file mode 100755
> index 0000000..a8a43c7
> --- /dev/null
> +++ b/testsuite/reloc12.sh
> @@ -0,0 +1,20 @@
> +#!/bin/bash
> +. `dirname $0`/functions.sh
> +rm -f reloc12 reloc12lib*.so reloc12.log
> +rm -f prelink.cache
> +$RUN_HOST $CC -shared -O2 -fpic -o reloc12lib1.so $srcdir/reloc12lib1.c
> +$RUN_HOST $CC -shared -O2 -fpic -o reloc12lib2.so $srcdir/reloc12lib2.c
> +BINS="reloc12"
> +LIBS="reloc12lib1.so reloc12lib2.so"
> +$RUN_HOST $CCLINK -o reloc12 $srcdir/reloc12.c -Wl,--rpath-link,. ${LIBS}
> +savelibs
> +echo $PRELINK ${PRELINK_OPTS--vm} ./reloc12 > reloc12.log
> +$RUN_HOST $PRELINK ${PRELINK_OPTS--vm} ./reloc12 >> reloc12.log 2>&1 || exit 1
> +grep -q ^`echo $PRELINK | sed 's/ .*$/: /'` reloc12.log && exit 2
> +if [ "x$CROSS" = "x" ]; then
> + $RUN LD_LIBRARY_PATH=. ./reloc12 || exit 3
> +fi
> +$RUN_HOST $READELF -a ./reloc12 >> reloc12.log 2>&1 || exit 4
> +# So that it is not prelinked again
> +chmod -x ./reloc12
> +comparelibs >> reloc12.log 2>&1 || exit 5
> diff --git a/testsuite/reloc12lib1.c b/testsuite/reloc12lib1.c
> new file mode 100644
> index 0000000..db7e64f
> --- /dev/null
> +++ b/testsuite/reloc12lib1.c
> @@ -0,0 +1,11 @@
> +#include "reloc12.h"
> +
> +char a(const A *d)
> +{
> +  return d ? d->a : 0;
> +}
> +
> +int b(const A *d)
> +{
> +  return d ? d->b : -1;
> +}
> diff --git a/testsuite/reloc12lib2.c b/testsuite/reloc12lib2.c
> new file mode 100644
> index 0000000..ffa60a0
> --- /dev/null
> +++ b/testsuite/reloc12lib2.c
> @@ -0,0 +1,16 @@
> +#include "reloc12.h"
> +
> +A foo[] = {
> +  { 'b', 0 },
> +  { 'a', 1 },
> +  { 'r', 2 }
> +};
> +
> +A* find(char a)
> +{
> +  for(A* ptr = foo; ptr < foo + sizeof(foo)/sizeof(foo[0]); ptr++)
> +    if(ptr->a == a)
> +      return ptr;
> +
> +  return 0;
> +}
>