From 1fbbd6844e6a84e5d166ab475dc298d3b89fa4bf Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Mon, 27 Mar 2006 01:14:39 -0800 Subject: [PATCH] [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 Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 ecf107ae5ac8..198e59163288 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;