path: root/scripts/genksyms/parse.y
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authorRichard Yao <richard.yao@clusterhq.com>2015-07-20 19:52:48 -0400
committerMichal Marek <mmarek@suse.com>2015-08-20 14:55:55 +0200
commit1c722503fa81888c936a8d1a5052daec859f1a7c (patch)
tree4f314cb4e46e0eb0572fa92821b3bcef301c582f /scripts/genksyms/parse.y
parent9bebe9e5b0f3109a14000df25308c2971f872605 (diff)
genksyms: Duplicate function pointer type definitions segfault
I noticed that genksyms will segfault when it sees duplicate function pointer type declaration when I placed the same function pointer definition in two separate headers in a local branch as an intermediate step of some refactoring. This can be reproduced by piping the following minimal test case into `genksyms -r /dev/null` or alternatively, putting it into a C file attempting a build: typedef int (*f)(); typedef int (*f)(); Attaching gdb to genksyms to understand this failure is useless without changing CFLAGS to emit debuginfo. Once you have debuginfo, you will find that the failure is that `char *s` was NULL and the program executed `while(*s)`. At which point, further debugging requires familiarity with compiler front end / parser development. What happens is that flex identifies the first instance of the token "f" as IDENT and the yacc parser adds it to the symbol table. On the second instance, flex will identify "f" as TYPE, which triggers an error case in the yacc parser. Given that TYPE would have been IDENT had it not been in the symbol table, the the segmentaion fault could be avoided by treating TYPE as IDENT in the affected rule. Some might consider placing identical function pointer type declarations in different headers to be poor style might consider a failure to be beneficial. However, failing through a segmentation fault makes the cause non-obvious and can waste the time of anyone who encounters it. Signed-off-by: Richard Yao <richard.yao@clusterhq.com> Acked-by: Madhuri Yechuri <madhuriyechuri@clusterhq.com> Signed-off-by: Michal Marek <mmarek@suse.com>
Diffstat (limited to 'scripts/genksyms/parse.y')
1 files changed, 9 insertions, 0 deletions
diff --git a/scripts/genksyms/parse.y b/scripts/genksyms/parse.y
index b9f4cf202302..723ab30fe9d4 100644
--- a/scripts/genksyms/parse.y
+++ b/scripts/genksyms/parse.y
@@ -303,6 +303,15 @@ direct_declarator:
$$ = $1;
+ | TYPE
+ { if (current_name != NULL) {
+ error_with_pos("unexpected second declaration name");
+ } else {
+ current_name = (*$1)->string;
+ $$ = $1;
+ }
+ }
| direct_declarator '(' parameter_declaration_clause ')'
{ $$ = $4; }
| direct_declarator '(' error ')'