From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH] cgroup: fix broken file xattrs Date: Thu, 18 Apr 2013 23:13:03 -0700 Message-ID: <20130419061303.GB9691@mtj.dyndns.org> References: <5170DBC1.3020201@huawei.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:sender:date:from:to:cc:subject:message-id:references :mime-version:content-type:content-disposition:in-reply-to :user-agent; bh=twpGQlE53NlqyywJHCTC/MWxCG5J/dn4vQ+ey/nQ6U4=; b=ywwFhWst3PjNSM/Ab372vT74IZ0wweBSOwSm8zbhU2taff7RZnCOtnJxbG5DVK7ZHR 8/ISl3U1z5aDtIMSmvT41+WNMZ5GKxM380/+Hr2zWt57IrRbH2JgXSnI2NUtfLRPVwcM m+6/giF7eJ8wYK7GTpd72SzVDDELxaeAXCz3ANeMSPiQT1ul0ZOA8ufi1X2PH/RT++R7 zE60eRaLNF4pEwJ81IVueWL1HRNg2Pwo7MWAQsl9MTYZh4ZYDkszUzK4+fDPSqLlWzs/ uoggthAVHtWtLlB01zb3oM2A19542jvHvhqUC/ZW2usHPX8Tk83U9JRfUXZKBWnmj/hT c+Vw== Content-Disposition: inline In-Reply-To: <5170DBC1.3020201-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Li Zefan Cc: Aristeu Rozanski , LKML , Cgroups , Dan Carpenter , alexey.kodanev-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, Containers >From 712317ad97f41e738e1a19aa0a6392a78a84094e Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Thu, 18 Apr 2013 23:09:52 -0700 We should store file xattrs in struct cfent instead of struct cftype, because cftype is a type while cfent is object instance of cftype. For example each cgroup has a tasks file, and each tasks file is associated with a uniq cfent, but all those files share the same struct cftype. Alexey Kodanev reported a crash, which can be reproduced: # mount -t cgroup -o xattr /sys/fs/cgroup # mkdir /sys/fs/cgroup/test # setfattr -n trusted.value -v test_value /sys/fs/cgroup/tasks # rmdir /sys/fs/cgroup/test # umount /sys/fs/cgroup oops! In this case, simple_xattrs_free() will free the same struct simple_xattrs twice. tj: Dropped unused local variable @cft from cgroup_diput(). Cc: # 3.8.x Reported-by: Alexey Kodanev Signed-off-by: Li Zefan Signed-off-by: Tejun Heo --- Applied to cgroup/for-3.10 with slight modification. Thanks. include/linux/cgroup.h | 3 --- kernel/cgroup.c | 11 ++++++----- 2 files changed, 6 insertions(+), 8 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index cda7eb2..c371888 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -422,9 +422,6 @@ struct cftype { /* CFTYPE_* flags */ unsigned int flags; - /* file xattrs */ - struct simple_xattrs xattrs; - int (*open)(struct inode *inode, struct file *file); ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft, struct file *file, diff --git a/kernel/cgroup.c b/kernel/cgroup.c index c16719e..192d762 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -117,6 +117,9 @@ struct cfent { struct list_head node; struct dentry *dentry; struct cftype *type; + + /* file xattrs */ + struct simple_xattrs xattrs; }; /* @@ -882,13 +885,12 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) } else { struct cfent *cfe = __d_cfe(dentry); struct cgroup *cgrp = dentry->d_parent->d_fsdata; - struct cftype *cft = cfe->type; WARN_ONCE(!list_empty(&cfe->node) && cgrp != &cgrp->root->top_cgroup, "cfe still linked for %s\n", cfe->type->name); + simple_xattrs_free(&cfe->xattrs); kfree(cfe); - simple_xattrs_free(&cft->xattrs); } iput(inode); } @@ -2501,7 +2503,7 @@ static struct simple_xattrs *__d_xattrs(struct dentry *dentry) if (S_ISDIR(dentry->d_inode->i_mode)) return &__d_cgrp(dentry)->xattrs; else - return &__d_cft(dentry)->xattrs; + return &__d_cfe(dentry)->xattrs; } static inline int xattr_enabled(struct dentry *dentry) @@ -2677,8 +2679,6 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, umode_t mode; char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; - simple_xattrs_init(&cft->xattrs); - if (subsys && !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) { strcpy(name, subsys->name); strcat(name, "."); @@ -2703,6 +2703,7 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, cfe->type = (void *)cft; cfe->dentry = dentry; dentry->d_fsdata = cfe; + simple_xattrs_init(&cfe->xattrs); list_add_tail(&cfe->node, &parent->files); cfe = NULL; } -- 1.8.1.4