[Cook] deadlock in interrupt() at cook/desist.c:57

[Peter Miller]

On Wed, 2009-11-18 at 11:03 -0700, Martin Sebor wrote:
> I've had cook deadlock on me several times. From the stack trace
> and the source code it appears that it calls malloc() from a signal
> handler (invoked in response to SIGINT). Since malloc() is not
> async-signal safe, calling it from signal handlers is unsafe and
> leads to undefined behavior.

Does the attached patch fix the problem for you?
(As a side effect, it makes the interrupt message slightly less
responsive.)





-- 
Peter Miller <pmiller at opensource.org.au>
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MIME-Version: 1.0
Content-Type: application/aegis-patch
Subject: cook.2.32 - desist vs malloc
Content-Name: cook.2.32.C022.patch
Content-Disposition: attachment; filename=cook.2.32.C022.patch
X-Aegis-Project-Name: cook.2.32
X-Aegis-Change-Number: 22

#	
#	The desist interrupt handler could sometimes deadlock because it use
#	malloc (vis the error message printing functions).  This can cause
#	processes to hang.
#	
#	My thanks to Martin Sebor <msebor at gmail.com> for reporting this bug.
#	
# Aegis-Change-Set-Begin
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# Aegis-Change-Set-End
#
Index: cook/desist.c
--- cook/desist.c
+++ cook/desist.c
@@ -50,14 +50,7 @@
 static RETSIGTYPE
 interrupt(int n)
 {
-    sub_context_ty  *scp;
-
-    star_eoln();
-    desist_flag++;
-    scp = sub_context_new();
-    sub_var_set(scp, "Name", "%s", safe_strsignal(n));
-    error_intl(scp, i18n("interrupted by $name"));
-    sub_context_delete(scp);
+    desist_flag = n;
     signal(n, interrupt);
 }
 
@@ -79,9 +72,19 @@
 {
     int             result;
 
-    result = (desist_flag != 0);
+    result = desist_flag;
     desist_flag = 0;
-    return result;
+    if (result != 0)
+    {
+        sub_context_ty  *scp;
+
+        star_eoln();
+        scp = sub_context_new();
+        sub_var_set(scp, "Name", "%s", safe_strsignal(result));
+        error_intl(scp, i18n("interrupted by $name"));
+        sub_context_delete(scp);
+    }
+    return (result != 0);
 }