On Wed, Jul 17, 2024 at 10:51 AM HONG Yifan <elsk@xxxxxxxxxx> wrote: > > This prevents segfault when getting filename and lineno in recursive > checks. > > If the following snippet is found in Kconfig: > > [Test code 1] > > config FOO > bool > depends on BAR > select BAR > > ... without BAR defined; then there is a segfault. > > Kconfig:34:error: recursive dependency detected! > Kconfig:34: symbol FOO depends on BAR > make[4]: *** [scripts/kconfig/Makefile:85: allnoconfig] Segmentation fault > > This is because of the following. BAR is a fake entry created by > sym_lookup() with prop being NULL. In the recursive check, there is a > NULL check for prop to fall back to stack->sym->prop if stack->prop is > NULL. However, in this case, stack->sym points to the fake BAR entry > created by sym_lookup(), so prop is still NULL. prop was then referenced > without additional NULL checks, causing segfault. > > As the previous email thread suggests, the file and lineno for select is > also wrong: > > [Test code 2] > > config FOO > bool > > config BAR > bool > > config FOO > bool "FOO" > depends on BAR > select BAR > > $ make defconfig > *** Default configuration is based on 'x86_64_defconfig' > Kconfig:1:error: recursive dependency detected! > Kconfig:1: symbol FOO depends on BAR > Kconfig:4: symbol BAR is selected by FOO > [...] > > Kconfig:4 should be Kconfig:10. > > This patch deletes the wrong and segfault-prone filename/lineno > inference completely. With this patch, Test code 1 yields: > > error: recursive dependency detected! > symbol FOO depends on BAR > symbol BAR is selected by FOO > > Link: https://lore.kernel.org/linux-kbuild/20240627231919.2461945-1-elsk@xxxxxxxxxx/T/ > Link: https://lore.kernel.org/linux-kbuild/20240620211112.500465-1-elsk@xxxxxxxxxx/ > Link: https://lore.kernel.org/linux-kbuild/20240618185609.4096399-1-elsk@xxxxxxxxxx/ > Signed-off-by: HONG Yifan <elsk@xxxxxxxxxx> > > -- > v4: Rebased & addressed comments from masahiroy@xxxxxxxxxx. Simplify > code by dropping `prop` variable. > v3: Rebase on top of > https://lore.kernel.org/linux-kbuild/20240626182212.3758235-1-masahiroy@xxxxxxxxxx/T/#t > & resolve merge conflicts. Fix > scripts/kconfig/tests/err_recursive_dep/expected_stderr > v2: Delete all filenames/lineno completely as suggested by > masahiroy@xxxxxxxxxx Applied to linux-kbuild. Thanks! -- Best Regards Masahiro Yamada
