tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kconfig: require a space after '#' for valid input

Currently, when an input line starts with '#', (line + 2) is passed to
memcmp() without checking line[1].

It means that line[1] can be any arbitrary character. For example,
"#KCONFIG_FOO is not set" is accepted as valid input, functioning the
same as "# CONFIG_FOO is not set".

More importantly, this can potentially lead to a buffer overrun if
line[1] == '\0'. It occurs if the input only contains '#', as
(line + 2) points to an uninitialized buffer.

Check line[1], and skip the line if it is not a space.

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

Masahiro Yamada 4d137ab0 61e3e3c2

+2
+2
scripts/kconfig/confdata.c
··· 426 426 conf_lineno++; 427 427 sym = NULL; 428 428 if (line[0] == '#') { 429 + if (line[1] != ' ') 430 + continue; 429 431 if (memcmp(line + 2, CONFIG_, strlen(CONFIG_))) 430 432 continue; 431 433 p = strchr(line + 2 + strlen(CONFIG_), ' ');