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It can be accessed and reviewed at: https://github.com/lxc/lxc/pull/2261
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=== Description (from pull-request) ===
lxc_make_tmpfile() uses mkstemp() internally, and thus expects the
template to contain 'XX' and be writable.
The existing code in make_anonymous_mount_file() did not work in
case the memfd_create() syscall was not available.
Furthermore, mkstemp() modifies its template argument, hence it
should not be a constant, or undefined behavior can happen. Fixed
both occurrences.
//cc @thmo I tried to push directly to your branch but I think you opted out of this feature. So I'm doing a new pr here. It's really just coding OCD stuff. :)
From a324e7eba0d954ab6f9dafad09efaa67f4aeaa9e Mon Sep 17 00:00:00 2001
From: Christian Brauner
Date: Fri, 6 Apr 2018 10:54:02 +0200
Subject: [PATCH 1/2] conf: fix temporary file creation
lxc_make_tmpfile() uses mkstemp() internally, and thus expects the
template to contain 'XX' and be writable.
Signed-off-by: Thomas Moschny
Signed-off-by: Christian Brauner
---
src/lxc/conf.c | 5 -
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index 745584308..09095ff9f 100644
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -2286,9 +2286,12 @@ FILE *make_anonymous_mount_file(struct lxc_list *mount)
fd = memfd_create(".lxc_mount_file", MFD_CLOEXEC);
if (fd < 0) {
+ char template[] = P_tmpdir "/.lxc_mount_file_XX";
+
if (errno != ENOSYS)
return NULL;
- fd = lxc_make_tmpfile((char *){P_tmpdir "/.lxc_mount_file"},
true);
+
+ fd = lxc_make_tmpfile(template, true);
if (fd < 0) {
SYSERROR("Could not create temporary mount file");
return NULL;
From 709384a02e74f76d59dc6f2903aab1679e9b2839 Mon Sep 17 00:00:00 2001
From: Christian Brauner
Date: Fri, 6 Apr 2018 10:54:41 +0200
Subject: [PATCH 2/2] ringbuf: fix temporary file creation
lxc_make_tmpfile() uses mkstemp() internally, and thus expects the
template to contain 'XX' and be writable.
Signed-off-by: Thomas Moschny
Signed-off-by: Christian Brauner
---
src/lxc/ringbuf.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/src/lxc/ringbuf.c b/src/lxc/ringbuf.c
index 1299fe709..7aa2e6310 100644
--- a/src/lxc/ringbuf.c
+++ b/src/lxc/ringbuf.c
@@ -52,10 +52,12 @@ int lxc_ringbuf_create(struct lxc_ringbuf *buf, size_t size)
memfd = memfd_create(".lxc_ringbuf", MFD_CLOEXEC);
if (memfd < 0) {
+ char template[] = P_tmpdir "/.lxc_ringbuf_XX";
+
if (errno != ENOSYS)
goto on_error;
- memfd = lxc_make_tmpfile((char
*){P_tmpdir"/.lxc_ringbuf_XX"}, true);
+ memfd = lxc_make_tmpfile(template, true);
}
if (memfd < 0)
goto on_error;
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