[tip: objtool/core] objtool/klp: Normalize Module.symvers paths to module names
From: tip-bot2 for Joe Lawrence <hidden>
Date: 2026-08-03 05:49:46
Also in:
lkml
Subsystem:
objtool, the rest · Maintainers:
Josh Poimboeuf, Peter Zijlstra, Linus Torvalds
The following commit has been merged into the objtool/core branch of tip: Commit-ID: 8668bf91e0508abeb8e98b4edd89032be02228a1 Gitweb: https://git.kernel.org/tip/8668bf91e0508abeb8e98b4edd89032be02228a1 Author: Joe Lawrence [off-list ref] AuthorDate: Sun, 02 Aug 2026 20:24:24 -07:00 Committer: Ingo Molnar [off-list ref] CommitterDate: Mon, 03 Aug 2026 07:12:38 +02:00 objtool/klp: Normalize Module.symvers paths to module names Module.symvers contains build-tree object paths as module identifiers (e.g., "arch/x86/kvm/kvm") rather than runtime module names ("kvm"). Objtool's clone_reloc_klp() uses this field directly for exported symbols, while unexported symbols correctly go through __find_modname(). This means that exported symbol relocations may land in a .klp.rela section named with the build path rather than the module name. That is a crash waiting to happen: the kernel's livepatch loader silently skips this relocation because it doesn't match the expected klp_object name. The unresolved relocation sits in the newly activated code, crashing when executed. Normalize export->mod at Module.symvers read time using the same logic as __find_modname() (refactored into a shared normalize_modname() helper). Fixes: dd590d4d57eb ("objtool/klp: Introduce klp diff subcommand for diffing object files") Reported-by: Ben Procknow <redacted> Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Cc: live-patching@vger.kernel.org Link: https://patch.msgid.link/dbe1b72931bd3c31b751fd0729613d9f2226fff6.1785727106.git.jpoimboe@kernel.org --- tools/objtool/klp-diff.c | 49 +++++++++++++++++++++++++++------------ 1 file changed, 34 insertions(+), 15 deletions(-)
diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
index aeb99d5..15d37d9 100644
--- a/tools/objtool/klp-diff.c
+++ b/tools/objtool/klp-diff.c@@ -83,6 +83,35 @@ static char *escape_str(const char *orig) return new; } +/* + * Convert a build-tree object path to a runtime module name: strip + * directory components, replace '-' with '_', and remove file + * extensions. Examples: + * + * "arch/x86/kvm/kvm" -> "kvm" + * "arch/x86/kvm/kvm-intel" -> "kvm_intel". + * + * Used by read_exports() to normalize Module.symvers entries and by + * __find_modname() as a fallback when .modinfo lacks a "name=" tag. + */ +static char *normalize_modname(char *name) +{ + char *slash = strrchr(name, '/'); + + if (slash) + name = slash + 1; + + for (char *c = name; *c; c++) { + if (*c == '-') + *c = '_'; + else if (*c == '.') { + *c = '\0'; + break; + } + } + return name; +} + static int read_exports(void) { const char *symvers = "Module.symvers";
@@ -150,6 +179,9 @@ static int read_exports(void) return -1; } + if (strcmp(export->mod, "vmlinux")) + export->mod = normalize_modname(export->mod); + export->sym = strdup(sym); if (!export->sym) { ERROR_GLIBC("strdup");
@@ -1140,7 +1172,7 @@ static struct export *find_export(struct symbol *sym) static const char *__find_modname(struct elfs *e) { struct section *sec; - char *name, *slash; + char *name; sec = find_section_by_name(e->orig, ".modinfo"); if (!sec) {
@@ -1158,20 +1190,7 @@ static const char *__find_modname(struct elfs *e) return NULL; } - slash = strrchr(name, '/'); - if (slash) - name = slash + 1; - - for (char *c = name; *c; c++) { - if (*c == '-') - *c = '_'; - else if (*c == '.') { - *c = '\0'; - break; - } - } - - return name; + return normalize_modname(name); } /* Get the object's module name as defined by the kernel (and klp_object) */