[PATCH AUTOSEL 5.12 079/116] kconfig: nconf: stop endless search loops

[PATCH AUTOSEL 5.12 079/116] kconfig: nconf: stop endless search loops

[Sasha Levin]

From: Mihai Moldovan <ionic@ionic.de>

[ Upstream commit 8c94b430b9f6213dec84e309bb480a71778c4213 ]

If the user selects the very first entry in a page and performs a
search-up operation, or selects the very last entry in a page and
performs a search-down operation that will not succeed (e.g., via
[/]asdfzzz[Up Arrow]), nconf will never terminate searching the page.

The reason is that in this case, the starting point will be set to -1
or n, which is then translated into (n - 1) (i.e., the last entry of
the page) or 0 (i.e., the first entry of the page) and finally the
search begins. This continues to work fine until the index reaches 0 or
(n - 1), at which point it will be decremented to -1 or incremented to
n, but not checked against the starting point right away. Instead, it's
wrapped around to the bottom or top again, after which the starting
point check occurs... and naturally fails.

My original implementation added another check for -1 before wrapping
the running index variable around, but Masahiro Yamada pointed out that
the actual issue is that the comparison point (starting point) exceeds
bounds (i.e., the [0,n-1] interval) in the first place and that,
instead, the starting point should be fixed.

This has the welcome side-effect of also fixing the case where the
starting point was n while searching down, which also lead to an
infinite loop.

OTOH, this code is now essentially all his work.

Amazingly, nobody seems to have been hit by this for 11 years - or at
the very least nobody bothered to debug and fix this.

Signed-off-by: Mihai Moldovan <ionic@ionic.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 scripts/kconfig/nconf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/kconfig/nconf.c b/scripts/kconfig/nconf.c
index e0f965529166..af814b39b876 100644
--- a/scripts/kconfig/nconf.c
+++ b/scripts/kconfig/nconf.c
@@ -504,8 +504,8 @@ static int get_mext_match(const char *match_str, match_f flag)
 	else if (flag == FIND_NEXT_MATCH_UP)
 		--match_start;
 
+	match_start = (match_start + items_num) % items_num;
 	index = match_start;
-	index = (index + items_num) % items_num;
 	while (true) {
 		char *str = k_menu_items[index].str;
 		if (strcasestr(str, match_str) != NULL)
-- 
2.30.2

[PATCH AUTOSEL 5.12 108/116] kbuild: generate Module.symvers only when vmlinux exists

[Sasha Levin]

From: Masahiro Yamada <masahiroy@kernel.org>

[ Upstream commit 69bc8d386aebbd91a6bb44b6d33f77c8dfa9ed8c ]

The external module build shows the following warning if Module.symvers
is missing in the kernel tree.

  WARNING: Symbol version dump "Module.symvers" is missing.
           Modules may not have dependencies or modversions.

I think this is an important heads-up because the resulting modules may
not work as expected. This happens when you did not build the entire
kernel tree, for example, you might have prepared the minimal setups
for external modules by 'make defconfig && make modules_preapre'.

A problem is that 'make modules' creates Module.symvers even without
vmlinux. In this case, that warning is suppressed since Module.symvers
already exists in spite of its incomplete content.

The incomplete (i.e. invalid) Module.symvers should not be created.

This commit changes the second pass of modpost to dump symbols into
modules-only.symvers. The final Module.symvers is created by
concatenating vmlinux.symvers and modules-only.symvers if both exist.

Module.symvers is supposed to collect symbols from both vmlinux and
modules. It might be a bit confusing, and I am not quite sure if it
is an official interface, but presumably it is difficult to rename it
because some tools (e.g. kmod) parse it.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 .gitignore               |  1 +
 Documentation/dontdiff   |  1 +
 Makefile                 |  2 +-
 scripts/Makefile.modpost | 15 ++++++++++++++-
 scripts/mod/modpost.c    | 15 +--------------
 5 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/.gitignore b/.gitignore
index 3af66272d6f1..127012c1f717 100644
--- a/.gitignore
+++ b/.gitignore
@@ -57,6 +57,7 @@ modules.order
 /tags
 /TAGS
 /linux
+/modules-only.symvers
 /vmlinux
 /vmlinux.32
 /vmlinux.symvers
diff --git a/Documentation/dontdiff b/Documentation/dontdiff
index e361fc95ca29..82e3eee7363b 100644
--- a/Documentation/dontdiff
+++ b/Documentation/dontdiff
@@ -178,6 +178,7 @@ mktables
 mktree
 mkutf8data
 modpost
+modules-only.symvers
 modules.builtin
 modules.builtin.modinfo
 modules.nsdeps
diff --git a/Makefile b/Makefile
index 78b0941f0de4..50c82ed67f6d 100644
--- a/Makefile
+++ b/Makefile
@@ -1513,7 +1513,7 @@ endif # CONFIG_MODULES
 # make distclean Remove editor backup files, patch leftover files and the like
 
 # Directories & files removed with 'make clean'
-CLEAN_FILES += include/ksym vmlinux.symvers \
+CLEAN_FILES += include/ksym vmlinux.symvers modules-only.symvers \
 	       modules.builtin modules.builtin.modinfo modules.nsdeps \
 	       compile_commands.json .thinlto-cache
 
diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index 066beffca09a..4ca5579af4e4 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -68,7 +68,20 @@ else
 ifeq ($(KBUILD_EXTMOD),)
 
 input-symdump := vmlinux.symvers
-output-symdump := Module.symvers
+output-symdump := modules-only.symvers
+
+quiet_cmd_cat = GEN     $@
+      cmd_cat = cat $(real-prereqs) > $@
+
+ifneq ($(wildcard vmlinux.symvers),)
+
+__modpost: Module.symvers
+Module.symvers: vmlinux.symvers modules-only.symvers FORCE
+	$(call if_changed,cat)
+
+targets += Module.symvers
+
+endif
 
 else
 
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 24725e50c7b4..10c3fba26f03 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2423,19 +2423,6 @@ static void read_dump(const char *fname)
 	fatal("parse error in symbol dump file\n");
 }
 
-/* For normal builds always dump all symbols.
- * For external modules only dump symbols
- * that are not read from kernel Module.symvers.
- **/
-static int dump_sym(struct symbol *sym)
-{
-	if (!external_module)
-		return 1;
-	if (sym->module->from_dump)
-		return 0;
-	return 1;
-}
-
 static void write_dump(const char *fname)
 {
 	struct buffer buf = { };
@@ -2446,7 +2433,7 @@ static void write_dump(const char *fname)
 	for (n = 0; n < SYMBOL_HASH_SIZE ; n++) {
 		symbol = symbolhash[n];
 		while (symbol) {
-			if (dump_sym(symbol)) {
+			if (!symbol->module->from_dump) {
 				namespace = symbol->namespace;
 				buf_printf(&buf, "0x%08x\t%s\t%s\t%s\t%s\n",
 					   symbol->crc, symbol->name,
-- 
2.30.2