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kpatch-build: Check exported symbol version changes 

The CRCs of exported symbols Module.symvers can differ between the
original build and the patched build.

In such a case, it is probably wise to rework the patch to avoid such
modifications.

Warn when a symbol changes version in the exported symbol list.

Fixes issue #1084

Signed-off-by: Julien Thierry <jthierry@redhat.com>
This commit is contained in:
Julien Thierry 2020-05-20 12:51:39 +01:00
parent b4c2753684
commit e9600c5513
1 changed files with 28 additions and 0 deletions
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28
kpatch-build/kpatch-build
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@ -745,6 +745,7 @@ USE_KLP_ARCH=0
CONFIG_PARAVIRT=0
CONFIG_UNWINDER_ORC=0
CONFIG_JUMP_LABEL=0
CONFIG_MODVERSIONS=0
if grep -q "CONFIG_LIVEPATCH=y" "$CONFIGFILE" && (kernel_is_rhel || kernel_version_gte 4.9.0); then
@ -770,6 +771,7 @@ fi
grep -q "CONFIG_PARAVIRT=y" "$CONFIGFILE" && CONFIG_PARAVIRT=1
grep -q "CONFIG_UNWINDER_ORC=y" "$CONFIGFILE" && CONFIG_UNWINDER_ORC=1
grep -q "CONFIG_JUMP_LABEL=y" "$CONFIGFILE" && CONFIG_JUMP_LABEL=1
grep -q "CONFIG_MODVERSIONS=y" "$CONFIGFILE" && CONFIG_MODVERSIONS=1
# unsupported kernel option checking
grep -q "CONFIG_DEBUG_INFO_SPLIT=y" "$CONFIGFILE" && die "kernel option 'CONFIG_DEBUG_INFO_SPLIT' not supported"
@ -805,6 +807,9 @@ unset KPATCH_GCC_TEMPDIR
# shellcheck disable=SC2086
CROSS_COMPILE="$TOOLSDIR/kpatch-gcc " make "-j$CPUS" $TARGETS 2>&1 | logger || die
# Save original module symvers
cp "$SRCDIR/Module.symvers" "$TEMPDIR/Module.symvers"
echo "Building patched source"
apply_patches
mkdir -p "$TEMPDIR/orig" "$TEMPDIR/patched"
@ -831,6 +836,29 @@ fi
[[ -n "$OOT_MODULE" ]] || grep -q vmlinux "$SRCDIR/Module.symvers" || die "truncated $SRCDIR/Module.symvers file"
if [[ "$CONFIG_MODVERSIONS" -eq 1 ]]; then
while read -ra sym_line; do
if [[ ${#sym_line[@]} -lt 4 ]]; then
die "Malformed ${TEMPDIR}/Module.symvers file"
fi
sym=${sym_line[1]}
read -ra patched_sym_line <<< "$(grep "\s$sym\s" "$SRCDIR/Module.symvers")"
if [[ ${#patched_sym_line[@]} -lt 4 ]]; then
die "Malformed symbol entry for ${sym} in ${SRCDIR}/Module.symvers file"
fi
# Assume that both original and patched symvers have the same format.
# In both cases, the symbol should have the same CRC, belong to the same
# Module/Namespace and have the same export type.
if [[ ${#sym_line[@]} -ne ${#patched_sym_line[@]} || \
"${sym_line[*]}" != "${patched_sym_line[*]}" ]]; then
warn "Version disagreement for symbol ${sym}"
fi
done < "${TEMPDIR}/Module.symvers"
fi
# Read as words, no quotes.
# shellcheck disable=SC2013
for i in $(cat "$TEMPDIR/changed_objs")