[ Upstream commit be2fa44b5180a1f021efb40c55fdf63c249c3209 ]

When a symbol that is already registered is read again from *.symref
file, __add_symbol() removes the previous one from the hash table without
freeing it.

[Test Case]

  $ cat foo.c
  #include <linux/export.h>
  void foo(void);
  void foo(void) {}
  EXPORT_SYMBOL(foo);

  $ cat foo.symref
  foo void foo ( void )
  foo void foo ( void )

When a symbol is removed from the hash table, it must be freed along
with its ->name and ->defn members. However, sym->name cannot be freed
because it is sometimes shared with node->string, but not always. If
sym->name and node->string share the same memory, free(sym->name) could
lead to a double-free bug.

To resolve this issue, always assign a strdup'ed string to sym->name.

Fixes: 64e6c1e12372 ("genksyms: track symbol checksum changes")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 45c9c4101d3d2fdfa00852274bbebba65fcc3cf2 ]

When a symbol that is already registered is added again, __add_symbol()
returns without freeing the symbol definition, making it unreachable.

The following test cases demonstrate different memory leak points.

[Test Case 1]

Forward declaration with exactly the same definition

  $ cat foo.c
  #include <linux/export.h>
  void foo(void);
  void foo(void) {}
  EXPORT_SYMBOL(foo);

[Test Case 2]

Forward declaration with a different definition (e.g. attribute)

  $ cat foo.c
  #include <linux/export.h>
  void foo(void);
  __attribute__((__section__(".ref.text"))) void foo(void) {}
  EXPORT_SYMBOL(foo);

[Test Case 3]

Preserving an overridden symbol (compile with KBUILD_PRESERVE=1)

  $ cat foo.c
  #include <linux/export.h>
  void foo(void);
  void foo(void) { }
  EXPORT_SYMBOL(foo);

  $ cat foo.symref
  override foo void foo ( int )

The memory leaks in Test Case 1 and 2 have existed since the introduction
of genksyms into the kernel tree. [1]

The memory leak in Test Case 3 was introduced by commit 5dae9a550a74
("genksyms: allow to ignore symbol checksum changes").

When multiple init_declarators are reduced to an init_declarator_list,
the decl_spec must be duplicated. Otherwise, the following Test Case 4
would result in a double-free bug.

[Test Case 4]

  $ cat foo.c
  #include <linux/export.h>

  extern int foo, bar;

  int foo, bar;
  EXPORT_SYMBOL(foo);

In this case, 'foo' and 'bar' share the same decl_spec, 'int'. It must
be unshared before being passed to add_symbol().

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=46bd1da672d66ccd8a639d3c1f8a166048cca608

Fixes: 5dae9a550a74 ("genksyms: allow to ignore symbol checksum changes")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Make genksyms output symbol versions in the format modpost expects,
so the 'sed' is unneeded.

This commit makes *.symversions completely unneeded.

I will keep *.symversions in .gitignore and 'make clean' for a while.
Otherwise, 'git status' might be surprising.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)

include/{linux,asm-generic}/export.h defines a weak symbol, __crc_*
as a placeholder.

Genksyms writes the version CRCs into the linker script, which will be
used for filling the __crc_* symbols. The linker script format depends
on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset
to the reference of CRC.

It is time to get rid of this complexity.

Now that modpost parses text files (.*.cmd) to collect all the CRCs,
it can generate C code that will be linked to the vmlinux or modules.

Generate a new C file, .vmlinux.export.c, which contains the CRCs of
symbols exported by vmlinux. It is compiled and linked to vmlinux in
scripts/link-vmlinux.sh.

Put the CRCs of symbols exported by modules into the existing *.mod.c
files. No additional build step is needed for modules. As before,
*.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal.

No linker magic is used here. The new C implementation works in the
same way, whether CONFIG_RELOCATABLE is enabled or not.
CONFIG_MODULE_REL_CRCS is no longer needed.

Previously, Kbuild invoked additional $(LD) to update the CRCs in
objects, but this step is unneeded too.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)

The pattern prefixed with '/' matches files in the same directory,
but not ones in sub-directories.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Andra Paraschiv <andraprs@amazon.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Gabriel Krisman Bertazi <krisman@collabora.com>

(shipped source) is a stale comment.

Since commit 833e62245943 ("genksyms: generate lexer and parser during
build instead of shipping"), there is no source file to be shipped in
this directory.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

This switch statement does not list out all the cases. Since the
'default' covers all the rest, the 'DOTS' case is unneeded.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

No one sets lexstate to ST_TABLE_*. It is is very old code, and I do
not know what was the plan at that time. Let's remove the dead code.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

This is only used in yylex() in lex.l

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

The C11 _Static_assert() keyword may be used at module scope, and we
need to teach genksyms about it to not abort with an error. We currently
have a growing number of static_assert() (but also direct usage of
_Static_assert()) users at module scope:

	git grep -E '^_Static_assert\(|^static_assert\(' | grep -v '^tools' | wc -l
	135

More recently, when enabling CONFIG_MODVERSIONS with CONFIG_KCSAN, we
observe a number of warnings:

	WARNING: modpost: EXPORT symbol "<..all kcsan symbols..>" [vmlinux] [...]

When running a preprocessed source through 'genksyms -w' a number of
syntax errors point at usage of static_assert()s. In the case of
kernel/kcsan/encoding.h, new static_assert()s had been introduced which
used expressions that appear to cause genksyms to not even be able to
recover from the syntax error gracefully (as it appears was the case
previously).

Therefore, make genksyms ignore all _Static_assert() and the contained
expression. With the fix, usage of _Static_assert() no longer cause
"syntax error" all over the kernel, and the above modpost warnings for
KCSAN are gone, too.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>