Don't kill already-reaped process.

* process.c (process_send_signal): Fix race condition where a
subprocess was reaped by a signal handler between the check for
liveness and calling 'kill', which meant that Emacs could in
theory kill an innocent bystander process.  Do the fix by blocking
SIGCHLD in a critical section that checks liveness before killing.

Fixes: debbugs:17561

1 files changed, 9 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 247ec1c34b4..d2db6ccebd6 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,12 @@
+2014-05-27  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Don't kill already-reaped process (Bug#17561).
+        * process.c (process_send_signal): Fix race condition where a
+        subprocess was reaped by a signal handler between the check for
+        liveness and calling 'kill', which meant that Emacs could in
+        theory kill an innocent bystander process.  Do the fix by blocking
+        SIGCHLD in a critical section that checks liveness before killing.
+
 2014-05-26  Eli Zaretskii  <eliz@gnu.org>
 
         * w32.c (_ANONYMOUS_UNION, _ANONYMOUS_STRUCT): Define only if