Attachment 13767 Details for Bug 13130 – git-am fix submitted to master.

[patch] git-am fix submitted to master.

0001-tevent-Fix-a-race-condition.patch (text/plain), 1.89 KB, created by Jeremy Allison on 2017-11-10 22:22:23 UTC

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Creator: Jeremy Allison

Created: 2017-11-10 22:22:23 UTC

Size: 1.89 KB

patch

obsolete

>From 75f163dbcbd46922934e24cac6d4b7101e06321d Mon Sep 17 00:00:00 2001
>From: Volker Lendecke <vl@samba.org>
>Date: Fri, 10 Nov 2017 21:22:26 +0100
>Subject: [PATCH] tevent: Fix a race condition
>
>We can't rely on tctx to exist after we unlocked the mutex. It took a
>while, but this does lead to data corruption. If *tctx is replaced with
>something where tctx->wakeup_fd points to a real, existing file
>descriptor, we're screwed. And by screwed, this means file corruption
>on disk.
>
>Again. I am not tall enough for this business.
>
>http://bholley.net/blog/2015/must-be-this-tall-to-write-multi-threaded-code.html
>
>BUG: https://bugzilla.samba.org/show_bug.cgi?id=13130
>
>Signed-off-by: Volker Lendecke <vl@samba.org>
>Reviewed-by: Jeremy Allison <jra@samba.org>
>---
> lib/tevent/tevent_threads.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
>diff --git a/lib/tevent/tevent_threads.c b/lib/tevent/tevent_threads.c
>index 4d1a8805181..2e83f1b66c2 100644
>--- a/lib/tevent/tevent_threads.c
>+++ b/lib/tevent/tevent_threads.c
>@@ -451,7 +451,7 @@ void _tevent_threaded_schedule_immediate(struct tevent_threaded_context *tctx,
> {
> #ifdef HAVE_PTHREAD
> 	struct tevent_context *ev;
>-	int ret;
>+	int ret, wakeup_fd;
> 
> 	ret = pthread_mutex_lock(&tctx->event_ctx_mutex);
> 	if (ret != 0) {
>@@ -495,6 +495,8 @@ void _tevent_threaded_schedule_immediate(struct tevent_threaded_context *tctx,
> 		abort();
> 	}
> 
>+	wakeup_fd = tctx->wakeup_fd;
>+
> 	ret = pthread_mutex_unlock(&tctx->event_ctx_mutex);
> 	if (ret != 0) {
> 		abort();
>@@ -510,7 +512,7 @@ void _tevent_threaded_schedule_immediate(struct tevent_threaded_context *tctx,
> 	 * than a noncontended one. So I'd opt for the lower footprint
> 	 * initially. Maybe we have to change that later.
> 	 */
>-	tevent_common_wakeup_fd(tctx->wakeup_fd);
>+	tevent_common_wakeup_fd(wakeup_fd);
> #else
> 	/*
> 	 * tevent_threaded_context_create() returned NULL with ENOSYS...
>-- 
>2.15.0.448.gf294e3d99a-goog
>

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