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SubjectRe: [PATCH] kconfig: undefined symbols can crash dependency loop detection
On 5.2.2011 00:16, Ulf Magnusson wrote:
> The Kconfig
>
> config FOO
> bool "FOO" if BAR
> select BAR
>
> has a dependency loop involving an undefined symbol BAR. This causes a
> segfault in sym_check_print_recursive() as it assumes all symbols have a
> non-null 'prop', which is not the case for undefined symbols. This is a
> proposed fix.
>
> Signed-off-by: Ulf Magnusson <ulfalizer.lkml@gmail.com>
> ---
> scripts/kconfig/symbol.c | 32 ++++++++++++++++++++++++++++----
> 1 files changed, 28 insertions(+), 4 deletions(-)
>
> diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
> index a796c95..81a217f 100644
> --- a/scripts/kconfig/symbol.c
> +++ b/scripts/kconfig/symbol.c
> @@ -5,6 +5,7 @@
>
> #include <ctype.h>
> #include <stdlib.h>
> +#include <stdio.h>
> #include <string.h>
> #include <regex.h>
> #include <sys/utsname.h>
> @@ -972,6 +973,10 @@ static void sym_check_print_recursive(struct symbol *last_sym)
> struct menu *menu = NULL;
> struct property *prop;
> struct dep_stack cv_stack;
> + const char *filename;
> + int lineno;
> + char undef_msg_buf[100];
> + int snprintf_size;
>
> if (sym_is_choice_value(last_sym)) {
> dep_stack_insert(&cv_stack, last_sym);
> @@ -1001,18 +1006,37 @@ static void sym_check_print_recursive(struct symbol *last_sym)
> break;
> }
> }
> +
> + if (prop) {
> + filename = prop->file->name;
> + lineno = prop->lineno;
> + } else {
> + /* The dependency loop involves an undefined symbol.
> + * Checking sym->name is probably unnecessary here, but
> + * just to be on the safe side. */
> + snprintf_size = snprintf(undef_msg_buf,
> + sizeof(undef_msg_buf),
> + "<no file, %s is undefined>",
> + sym->name ? sym->name :
> + "<choice>");
> + if (snprintf_size > sizeof(undef_msg_buf))
> + undef_msg_buf[sizeof(undef_msg_buf) - 1] = '\0';
> + filename = undef_msg_buf;
> + lineno = 0;

Good catch. But as this handles a corner case involving a severely
borken Kconfig file, I would simply do
filename = "<unknown>";
lineno = 0;
and be done with it.

Michal


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