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Subject[PATCH] kconfig: undefined symbols can crash dependency loop detection
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;
+ }
+
if (stack->sym == last_sym)
fprintf(stderr, "%s:%d:error: recursive dependency detected!\n",
- prop->file->name, prop->lineno);
+ filename, lineno);
if (stack->expr) {
fprintf(stderr, "%s:%d:\tsymbol %s %s value contains %s\n",
- prop->file->name, prop->lineno,
+ filename, lineno,
sym->name ? sym->name : "<choice>",
prop_get_type_name(prop->type),
next_sym->name ? next_sym->name : "<choice>");
} else if (stack->prop) {
fprintf(stderr, "%s:%d:\tsymbol %s depends on %s\n",
- prop->file->name, prop->lineno,
+ filename, lineno,
sym->name ? sym->name : "<choice>",
next_sym->name ? next_sym->name : "<choice>");
} else if (sym_is_choice(sym)) {
@@ -1027,7 +1051,7 @@ static void sym_check_print_recursive(struct symbol *last_sym)
next_sym->name ? next_sym->name : "<choice>");
} else {
fprintf(stderr, "%s:%d:\tsymbol %s is selected by %s\n",
- prop->file->name, prop->lineno,
+ filename, lineno,
sym->name ? sym->name : "<choice>",
next_sym->name ? next_sym->name : "<choice>");
}
--
1.7.0.4


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