From 2396669f0116cda9d5f2e0e19ce38c840731bc17 Mon Sep 17 00:00:00 2001 From: Simon Schubert Date: Thu, 9 Jul 2009 23:24:35 +0200 Subject: [PATCH] dma: prevent races from sharing fd between children On fork, fds are shared between children. If two processes work on different recipients, but on the same queue file, they might get confused when the fd (and thus the offset) is shared. Prevent this by re-opening the fd after fork. Reported-by: Daniel Roethlisberger --- libexec/dma/dma.c | 12 ++++++++++++ 1 files changed, 12 insertions(+), 0 deletions(-) diff --git a/libexec/dma/dma.c b/libexec/dma/dma.c index 4633b0c..793e327 100644 --- a/libexec/dma/dma.c +++ b/libexec/dma/dma.c @@ -484,6 +484,7 @@ go_background(struct queue *queue) { struct sigaction sa; struct qitem *it; + FILE *newqf; pid_t pid; if (daemonize && daemon(0, 0) != 0) { @@ -515,6 +516,17 @@ go_background(struct queue *queue) * * return and deliver mail */ + /* + * We have to prevent sharing of fds between children, so + * we have to dup the queue fd. + */ + newqf = fdopen(fileno(it->queuef), "r"); + if (newqf == NULL) { + syslog(LOG_ERR, "can not dup queue fd: %m"); + exit(1); + } + fclose(it->queuef); + it->queuef = newqf; return (it); default: -- 1.6.2.149.g6462