kernel/linux.git/scripts/genksyms, branch v5.10.257

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

2025-03-13T11:46:58+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

2025-03-13T11:46:58+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

genksyms: keywords: Use __restrict not _restrict

2020-08-18T11:16:46+00:00

Use the proper form of the RESTRICT keyword. Quote the comments properly too. Signed-off-by: Joe Perches Acked-by: Nick Desaulniers Signed-off-by: Masahiro Yamada

kbuild: introduce hostprogs-always-y and userprogs-always-y

2020-08-09T16:32:59+00:00

To build host programs, you need to add the program names to 'hostprogs' to use the necessary build rule, but it is not enough to build them because there is no dependency. There are two types of host programs: built as the prerequisite of another (e.g. gen_crc32table in lib/Makefile), or always built when Kbuild visits the Makefile (e.g. genksyms in scripts/genksyms/Makefile). The latter is typical in Makefiles under scripts/, which contains host programs globally used during the kernel build. To build them, you need to add them to both 'hostprogs' and 'always-y'. This commit adds hostprogs-always-y as a shorthand. The same applies to user programs. net/bpfilter/Makefile builds bpfilter_umh on demand, hence always-y is unneeded. In contrast, programs under samples/ are added to both 'userprogs' and 'always-y' so they are always built when Kbuild visits the Makefiles. userprogs-always-y works as a shorthand. Signed-off-by: Masahiro Yamada Acked-by: Miguel Ojeda

.gitignore: add SPDX License Identifier

2020-03-25T10:50:48+00:00

Add SPDX License Identifier to all .gitignore files. Signed-off-by: Masahiro Yamada Signed-off-by: Greg Kroah-Hartman

kbuild: rename hostprogs-y/always to hostprogs/always-y

2020-02-03T16:53:07+00:00

In old days, the "host-progs" syntax was used for specifying host programs. It was renamed to the current "hostprogs-y" in 2004. It is typically useful in scripts/Makefile because it allows Kbuild to selectively compile host programs based on the kernel configuration. This commit renames like follows: always -> always-y hostprogs-y -> hostprogs So, scripts/Makefile will look like this: always-$(CONFIG_BUILD_BIN2C) += ... always-$(CONFIG_KALLSYMS) += ... ... hostprogs := $(always-y) $(always-m) I think this makes more sense because a host program is always a host program, irrespective of the kernel configuration. We want to specify which ones to compile by CONFIG options, so always-y will be handier. The "always", "hostprogs-y", "hostprogs-m" will be kept for backward compatibility for a while. Signed-off-by: Masahiro Yamada

genksyms: convert to SPDX License Identifier for lex.l and parse.y

2019-09-14T02:40:13+00:00

I used the C comment style (/* ... */) for the flex and bison files as in Kconfig (scripts/kconfig/{lexer.l,parser.y}) Signed-off-by: Masahiro Yamada

export.h, genksyms: do not make genksyms calculate CRC of trimmed symbols

2019-09-14T02:40:13+00:00

Arnd Bergmann reported false-positive modpost warnings detected by his randconfig testing of linux-next. Actually, this happens under the combination of CONFIG_MODVERSIONS and CONFIG_TRIM_UNUSED_KSYMS since commit 15bfc2348d54 ("modpost: check for static EXPORT_SYMBOL* functions"). For example, arch/arm/config/multi_v7_defconfig + CONFIG_MODVERSIONS + CONFIG_TRIM_UNUSED_KSYMS produces the following false-positives: WARNING: "__lshrdi3" [vmlinux] is a static (unknown) WARNING: "__ashrdi3" [vmlinux] is a static (unknown) WARNING: "__aeabi_lasr" [vmlinux] is a static (unknown) WARNING: "__aeabi_llsr" [vmlinux] is a static (unknown) WARNING: "ftrace_set_clr_event" [vmlinux] is a static (unknown) WARNING: "__muldi3" [vmlinux] is a static (unknown) WARNING: "__aeabi_ulcmp" [vmlinux] is a static (unknown) WARNING: "__ucmpdi2" [vmlinux] is a static (unknown) WARNING: "__aeabi_lmul" [vmlinux] is a static (unknown) WARNING: "__bswapsi2" [vmlinux] is a static (unknown) WARNING: "__bswapdi2" [vmlinux] is a static (unknown) WARNING: "__ashldi3" [vmlinux] is a static (unknown) WARNING: "__aeabi_llsl" [vmlinux] is a static (unknown) The root cause of the problem is not in the modpost, but in the implementation of CONFIG_TRIM_UNUSED_KSYMS. If there is at least one untrimmed symbol in the file, genksyms is invoked to calculate CRC of *all* the exported symbols in that file even if some of them have been trimmed due to no caller existing. As a result, .tmp_*.ver files contain CRC of trimmed symbols, thus unneeded, orphan __crc* symbols are added to objects. It had been harmless until recently. With commit 15bfc2348d54 ("modpost: check for static EXPORT_SYMBOL* functions"), it is now harmful because the bogus __crc* symbols make modpost call sym_update_crc() to add the symbols to the hash table, but there is no one that clears the ->is_static member. I gave Fixes to the first commit that uncovered the issue, but the potential problem has long existed since commit f235541699bc ("export.h: allow for per-symbol configurable EXPORT_SYMBOL()"). Fixes: 15bfc2348d54 ("modpost: check for static EXPORT_SYMBOL* functions") Reported-by: Arnd Bergmann Signed-off-by: Masahiro Yamada Tested-by: Arnd Bergmann

kbuild: rename KBUILD_ENABLE_EXTRA_GCC_CHECKS to KBUILD_EXTRA_WARN

2019-09-06T14:46:52+00:00

KBUILD_ENABLE_EXTRA_GCC_CHECKS started as a switch to add extra warning options for GCC, but now it is a historical misnomer since we use it also for Clang, DTC, and even kernel-doc. Rename it to more sensible, shorter KBUILD_EXTRA_WARN. For the backward compatibility, KBUILD_ENABLE_EXTRA_GCC_CHECKS is still supported (but not advertised in the documentation). I also fixed up 'make help', and updated the documentation. Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Reviewed-by: Sedat Dilek

kbuild: make bison create C file and header in a single pattern rule

2019-08-13T16:10:42+00:00

We generally expect bison to create not only a C file, but also a header, which will be included from the lexer. Currently, Kbuild generates them in separate rules. So, for instance, when building Kconfig, you will notice bison is invoked twice: HOSTCC scripts/kconfig/conf.o HOSTCC scripts/kconfig/confdata.o HOSTCC scripts/kconfig/expr.o LEX scripts/kconfig/lexer.lex.c YACC scripts/kconfig/parser.tab.h HOSTCC scripts/kconfig/lexer.lex.o YACC scripts/kconfig/parser.tab.c HOSTCC scripts/kconfig/parser.tab.o HOSTCC scripts/kconfig/preprocess.o HOSTCC scripts/kconfig/symbol.o HOSTLD scripts/kconfig/conf Make handles such cases nicely in pattern rules [1]. Merge the two rules so that one invokcation of bison can generate both of them. HOSTCC scripts/kconfig/conf.o HOSTCC scripts/kconfig/confdata.o HOSTCC scripts/kconfig/expr.o LEX scripts/kconfig/lexer.lex.c YACC scripts/kconfig/parser.tab.[ch] HOSTCC scripts/kconfig/lexer.lex.o HOSTCC scripts/kconfig/parser.tab.o HOSTCC scripts/kconfig/preprocess.o HOSTCC scripts/kconfig/symbol.o HOSTLD scripts/kconfig/conf [1] Pattern rule GNU Make manual says: "Pattern rules may have more than one target. Unlike normal rules, this does not act as many different rules with the same prerequisites and recipe. If a pattern rule has multiple targets, make knows that the rule's recipe is responsible for making all of the targets. The recipe is executed only once to make all the targets. When searching for a pattern rule to match a target, the target patterns of a rule other than the one that matches the target in need of a rule are incidental: make worries only about giving a recipe and prerequisites to the file presently in question. However, when this file's recipe is run, the other targets are marked as having been updated themselves." https://www.gnu.org/software/make/manual/html_node/Pattern-Intro.html Signed-off-by: Masahiro Yamada