https://sourceware.org/bugzilla/show_bug.cgi?id=28639
Bug ID: 28639
Summary: Fixing invalid build-id section size with
--relocatable(-r) linker(ld) option
Product: binutils
Version: unspecified
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: ld
Assignee: unassigned at sourceware dot org
Reporter: vchernou at cisco dot com
Target Milestone: ---
Created attachment 13809
--> https://sourceware.org/bugzilla/attachment.cgi?id=13809&action=edit
patch for fixing issue
building of glibc 2.32 and later with option "-Wl,--build-id" produce libc.so.6
with section ".note.gnu.build-id" that have invalid(double, 0x48) section size.
It happens because glibc use sublibraries for linking libc.so.
ld produce this sublibraries with build-id section and on last linking stage
loads this sections as input for linking.
ld should create new(valid) ".note.gnu.build-id" into function
ldelf_setup_build_id on last linking stage but it skip creating because
build-id section already exists.
As result libc.so.6 contain ".note.gnu.build-id" with build-ids from
sublibraries and without valid build-id
Howto solved:
Ignoring ".note.gnu.build-id" on linker input fix this problem.
Linker input doesn't have invalid build-id sections on ldelf_setup_build_id
stage and create new(proper) one for output library/binary
Clang have it's own fix for this issue:
https://reviews.llvm.org/D42823
https://bugs.llvm.org/show_bug.cgi?id=36203
howto reproduce:
yocto:
cd GLIBC_RECIPE_WORKDIR
export
CMD_PREFIX="./recipe-sysroot-native/usr/bin/x86_64-iosxe-linux/x86_64-iosxe-linux";
export GCC="$CMD_PREFIX-gcc"; export RELF="$CMD_PREFIX-readelf"
echo "void f1(){}" >f1.c
echo "void f2(){}" >f2.c
$GCC f1.c -c -o f1.o
$GCC f2.c -c -o f2.o
$GCC f1.o -Wl,--build-id -nostdlib -nostartfiles -r -o f1
$GCC f2.o -Wl,--build-id -nostdlib -nostartfiles -r -o f2
$GCC ./f1 ./f2 -shared -Wl,--build-id -nostdlib -nostartfiles -o f.so
$RELF -S f.so | grep -E -A1 "note.gnu.bu"
ubuntu:
echo "void f1(){}" >f1.c
echo "void f2(){}" >f2.c
gcc f1.c -c -o f1.o
gcc f2.c -c -o f2.o
gcc f1.o -Wl,--build-id -nostdlib -nostartfiles -r -o f1
gcc f2.o -Wl,--build-id -nostdlib -nostartfiles -r -o f2
gcc ./f1 ./f2 -shared -Wl,--build-id -nostdlib -nostartfiles -o f.so
readelf -S f.so | grep -E -A1 "note.gnu.bu"
output:
without fix
[ 1] .note.gnu.bu[...] NOTE 0000000000000238 00000238
0000000000000048 0000000000000000 A 0 0 4
with fix
[ 1] .note.gnu.bu[...] NOTE 0000000000000238 00000238
0000000000000024 0000000000000000 A 0 0 4
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