[Xen-changelog] [xen master] xl: close nullfd after dup2'ing it to stdin

[patchbot@xxxxxxx]

commit bb1372884283100ad65efde1b6b66cc7669505e9
Author:     Ian Campbell <ian.campbell@xxxxxxxxxx>
AuthorDate: Wed Feb 17 10:39:40 2016 +0000
Commit:     Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CommitDate: Tue Mar 1 13:38:50 2016 +0000

    xl: close nullfd after dup2'ing it to stdin
    
    We assert that nullfd if not std{in,out,err} since that would result
    in closing one of the just dup2'd fds. For this to happen
    std{in,out,err} would have needed to be closed, at which point all
    sorts of other things could go wrong.
    
    CID: 1130519
    
    It was previously hypothesised[0] that fixing 1130516 would solve this
    too, but that appears to not have been the case.
    
    Compile tested only.
    
    [0] 
http://lists.xenproject.org/archives/html/xen-devel/2013-11/msg02931.html
    
    Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    Cc: andrew.cooper3@xxxxxxxxxx
    Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
 tools/libxl/xl_cmdimpl.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 09037ca..80d8781 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -499,12 +499,17 @@ static int do_daemonize(char *name, const char *pidfile)
 
     CHK_SYSCALL(logfile = open(fullname, O_WRONLY|O_CREAT|O_APPEND, 0644));
     free(fullname);
+    assert(logfile >= 3);
 
     CHK_SYSCALL(nullfd = open("/dev/null", O_RDONLY));
+    assert(nullfd >= 3);
+
     dup2(nullfd, 0);
     dup2(logfile, 1);
     dup2(logfile, 2);
 
+    close(nullfd);
+
     CHK_SYSCALL(daemon(0, 1));
 
     if (pidfile) {
--
generated by git-patchbot for /home/xen/git/xen.git#master

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