Re: Kconfig: conf segfault (with invalid kconfig contents)

From: Sam Ravnborg
Date: Sat Dec 27 2008 - 16:47:04 EST


On Tue, Oct 23, 2007 at 10:14:01PM -0500, Olof Johansson wrote:
> Hi,
>
> Sorry, no patch, just a bugreport. :)
>
> I did a mistake in some Kconfig changes (locally) and got a segfault
> from conf:
>
> #0 0x10005fe0 in sym_check_deps ()
> #1 0x10005f40 in sym_check_expr_deps ()
> #2 0x1000605c in sym_check_deps ()
> #3 0x1000f3f4 in conf_parse ()
> #4 0x10003824 in main ()
>
>
> The way to reproduce is simple. I just added the equivalent of this
> to arch/powerpc/Kconfig:
>
> ---
> config TEST1
> bool
> depends on TEST2 && PCI
> select TEST2
>
> config TEST2
> bool
> ---
>
> Neither TEST1 nor TEST2 exists in the existing .config when I run make
> oldconfig to reproduce.
>
> It's clearly invalid in that it depends on what it selects, but it should
> just abort instead.

Hi Olof.

BAsed on your nice small testcase I have finally looked at it
and fixed the bug. I forgot to credit you in the patch I sent
to lkml (and linux-kbuild) but I have done so in my local repository.

See updated commit below.

Sam

[PATCH 1/3] kconfig: improve readout when we hit recursive dependencies

Following sample:
config TEST1
bool
depends on TEST2 && PCI
select TEST2

config TEST2
bool

Will result in the following output:

Kconfig:1:error: found recursive dependency:
TEST1
-> TEST2 (arch/x86/Kconfig:6)
-> TEST1 (arch/x86/Kconfig:1)

The sample above gave a segmentation fault
which is also fixed by this patch.

To save the filename/lineno info add a new property P_SYMBOL
which is added each time we see a symbol definition.

Thanks to Olof for reporting and providing the sample Kconfig.

Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Reported-by: Olof Johansson <olof@xxxxxxxxx>
Cc: Olof Johansson <olof@xxxxxxxxx>
Cc: Roman Zippel <zippel@xxxxxxxxxxxxxx>
---
scripts/kconfig/expr.h | 1 +
scripts/kconfig/menu.c | 2 ++
scripts/kconfig/symbol.c | 11 ++++++++---
3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/scripts/kconfig/expr.h b/scripts/kconfig/expr.h
index 6408fef..d587895 100644
--- a/scripts/kconfig/expr.h
+++ b/scripts/kconfig/expr.h
@@ -132,6 +132,7 @@ enum prop_type {
P_SELECT, /* select BAR */
P_RANGE, /* range 7..100 (for a symbol) */
P_ENV, /* value from environment variable */
+ P_SYMBOL, /* where a symbol is defined */
};

struct property {
diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index 07ff8d1..aa0e2f2 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -55,6 +55,8 @@ void menu_add_entry(struct symbol *sym)
*last_entry_ptr = menu;
last_entry_ptr = &menu->next;
current_entry = menu;
+ if (sym)
+ menu_add_prop(P_SYMBOL, NULL, NULL, NULL);
}

void menu_end_entry(void)
diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
index 18f3e5c..474dae2 100644
--- a/scripts/kconfig/symbol.c
+++ b/scripts/kconfig/symbol.c
@@ -856,8 +856,9 @@ struct symbol *sym_check_deps(struct symbol *sym)
struct property *prop;

if (sym->flags & SYMBOL_CHECK) {
- fprintf(stderr, "%s:%d:error: found recursive dependency: %s",
- sym->prop->file->name, sym->prop->lineno,
+ fprintf(stderr, "%s:%d:error: found recursive dependency:\n",
+ sym->prop->file->name, sym->prop->lineno);
+ fprintf(stderr, "\t %s\n",
sym->name ? sym->name : "<choice>");
return sym;
}
@@ -877,7 +878,9 @@ struct symbol *sym_check_deps(struct symbol *sym)
}

if (sym2) {
- fprintf(stderr, " -> %s", sym->name ? sym->name : "<choice>");
+ fprintf(stderr, "\t -> %s (%s:%d)\n",
+ sym->name ? sym->name : "<choice>",
+ sym->prop->file->name, sym->prop->lineno);
if (sym2 == sym) {
fprintf(stderr, "\n");
zconfnerrs++;
@@ -937,6 +940,8 @@ const char *prop_get_type_name(enum prop_type type)
return "select";
case P_RANGE:
return "range";
+ case P_SYMBOL:
+ return "symbol";
case P_UNKNOWN:
break;
}
--
1.6.0.2.GIT

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