From 1fbbd6844e6a84e5d166ab475dc298d3b89fa4bf Mon Sep 17 00:00:00 2001
From: Jeff Dike <jdike@addtoit.com>
Date: Mon, 27 Mar 2006 01:14:39 -0800
Subject: [PATCH] uml: prevent umid theft
Behavior when booting two UMLs with the same umid was broken. The second one
would steal the umid. This fixes that, making the second UML take a random
umid instead.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
arch/um/os-Linux/umid.c | 33 +++++++++++++++++++++++----------
1 file changed, 23 insertions(+), 10 deletions(-)
diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c
index ecf107ae5a..198e591632 100644
--- a/arch/um/os-Linux/umid.c
+++ b/arch/um/os-Linux/umid.c
@@ -143,8 +143,10 @@ static int not_dead_yet(char *dir)
goto out_close;
}
- if((kill(p, 0) == 0) || (errno != ESRCH))
+ if((kill(p, 0) == 0) || (errno != ESRCH)){
+ printk("umid \"%s\" is already in use by pid %d\n", umid, p);
return 1;
+ }
err = actually_do_remove(dir);
if(err)
@@ -234,33 +236,44 @@ int __init make_umid(void)
err = mkdir(tmp, 0777);
if(err < 0){
err = -errno;
- if(errno != EEXIST)
+ if(err != -EEXIST)
goto err;
- if(not_dead_yet(tmp) < 0)
+ /* 1 -> this umid is already in use
+ * < 0 -> we couldn't remove the umid directory
+ * In either case, we can't use this umid, so return -EEXIST.
+ */
+ if(not_dead_yet(tmp) != 0)
goto err;
err = mkdir(tmp, 0777);
}
- if(err < 0){
- printk("Failed to create '%s' - err = %d\n", umid, err);
- goto err_rmdir;
+ if(err){
+ err = -errno;
+ printk("Failed to create '%s' - err = %d\n", umid, -errno);
+ goto err;
}
umid_setup = 1;
create_pid_file();
- return 0;
-
- err_rmdir:
- rmdir(tmp);
+ err = 0;
err:
return err;
}
static int __init make_umid_init(void)
{
+ if(!make_umid())
+ return 0;
+
+ /* If initializing with the given umid failed, then try again with
+ * a random one.
+ */
+ printk("Failed to initialize umid \"%s\", trying with a random umid\n",
+ umid);
+ *umid = '\0';
make_umid();
return 0;
--
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