kernel/linux.git/scripts/genksyms, branch v6.12.80

genksyms: fix memory leak when the same symbol is read from *.symref file

2025-02-08T08:58:09+00:00

[ 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 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 Signed-off-by: Sasha Levin

genksyms: fix memory leak when the same symbol is added from source

2025-02-08T08:58:09+00:00

[ 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 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 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 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 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 Signed-off-by: Sasha Levin

kbuild: use $(src) instead of $(srctree)/$(src) for source directory

2024-05-09T19:34:52+00:00

Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for checked-in source files. It is merely a convention without any functional difference. In fact, $(obj) and $(src) are exactly the same, as defined in scripts/Makefile.build: src := $(obj) When the kernel is built in a separate output directory, $(src) does not accurately reflect the source directory location. While Kbuild resolves this discrepancy by specifying VPATH=$(srctree) to search for source files, it does not cover all cases. For example, when adding a header search path for local headers, -I$(srctree)/$(src) is typically passed to the compiler. This introduces inconsistency between upstream and downstream Makefiles because $(src) is used instead of $(srctree)/$(src) for the latter. To address this inconsistency, this commit changes the semantics of $(src) so that it always points to the directory in the source tree. Going forward, the variables used in Makefiles will have the following meanings: $(obj) - directory in the object tree $(src) - directory in the source tree (changed by this commit) $(objtree) - the top of the kernel object tree $(srctree) - the top of the kernel source tree Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced with $(src). Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier

genksyms: use getopt_long() unconditionally

2023-11-28T02:22:50+00:00

getopt_long() is used by various tools in the kernel (e.g. Kconfig). It should be fine to use it all the time. Signed-off-by: Masahiro Yamada

genksyms: remove the remnant of the -s option

2023-11-28T02:22:50+00:00

Commit 74d931716151 ("genksyms: remove symbol prefix support") removed the -s (--symbol-prefix) option. Clean up the left-over. Signed-off-by: Masahiro Yamada

genksyms: adjust the output format to modpost

2022-05-24T07:33:20+00:00

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 Reviewed-by: Nicolas Schier Tested-by: Nathan Chancellor Tested-by: Sedat Dilek # LLVM-14 (x86-64)

kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS

2022-05-24T07:33:20+00:00

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 Tested-by: Nathan Chancellor Tested-by: Nicolas Schier Reviewed-by: Nicolas Schier Tested-by: Sedat Dilek # LLVM-14 (x86-64)

.gitignore: prefix local generated files with a slash

2021-05-01T15:43:35+00:00

The pattern prefixed with '/' matches files in the same directory, but not ones in sub-directories. Signed-off-by: Masahiro Yamada Acked-by: Miguel Ojeda Acked-by: Rob Herring Acked-by: Andra Paraschiv Acked-by: Greg Kroah-Hartman Acked-by: Gabriel Krisman Bertazi

genksyms: fix stale comment

2021-05-01T15:43:34+00:00

(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

genksyms: remove useless case DOTS

2021-02-16T03:01:45+00:00

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