[PATCH 7.2 0974/1815] objtool/klp: Fix module name normalization for paths with dots

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

7.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Josh Poimboeuf <jpoimboe@kernel.org>

[ Upstream commit 165affd6f095323d953b0ed5823ec4d0db3b7d0d ]

When .modinfo has no "name=" tag, __find_modname() falls back to
converting the object's build-tree path to a runtime module name by
stripping directory components, converting '-' to '_' and truncating the
file extension.

It does all that in a single pass over the entire path, so the first dot
anywhere in the path ends the name.  For an object built in a directory
whose name contains a dot, e.g. "drivers/foo-1.0/bar.o", the result is a
bogus module name.

Strip the directory components up front so only the basename is scanned
for the extension separator.

Fixes: dd590d4d57eb ("objtool/klp: Introduce klp diff subcommand for diffing object files")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: live-patching@vger.kernel.org
Link: https://patch.msgid.link/9017b4609553bed16674e8f924d34691cbc2b2c1.1785727106.git.jpoimboe@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/objtool/klp-diff.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
index f8787d7d14547..aeb99d572300c 100644
--- a/tools/objtool/klp-diff.c
+++ b/tools/objtool/klp-diff.c
@@ -1140,7 +1140,7 @@ static struct export *find_export(struct symbol *sym)
 static const char *__find_modname(struct elfs *e)
 {
 	struct section *sec;
-	char *name;
+	char *name, *slash;
 
 	sec = find_section_by_name(e->orig, ".modinfo");
 	if (!sec) {
@@ -1158,10 +1158,12 @@ 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 == '/')
-			name = c + 1;
-		else if (*c == '-')
+		if (*c == '-')
 			*c = '_';
 		else if (*c == '.') {
 			*c = '\0';
-- 
2.53.0