From bfd534c72bec682cbf1017e54f0749aac24840eb Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 13 Jan 2012 21:32:59 -0800 Subject: [PATCH] sysfs: Complain bitterly about attempts to remove files from nonexistent directories. commit ce597919361dcec97341151690e780eade2a9cf4 upstream. Recently an OOPS was observed from the usb serial io_ti driver when it tried to remove sysfs directories. Upon investigation it turns out this driver was always buggy and that a recent sysfs change had stopped guarding itself against removing attributes from sysfs directories that had already been removed. :( Historically we have been silent about attempting to files from nonexistent sysfs directories and have politely returned error codes. That has resulted in people writing broken code that ignores the error codes. Issue a kernel WARNING and a stack backtrace to make it clear in no uncertain terms that abusing sysfs is not ok, and the callers need to fix their code. This change transforms the io_ti OOPS into a more comprehensible error message and stack backtrace. Signed-off-by: Eric W. Biederman Reported-by: Wolfgang Frisch Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/file.c | 6 ++++++ fs/sysfs/inode.c | 5 ++++- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index d4e6080b4b2..779789af6e9 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -493,6 +493,12 @@ int sysfs_attr_ns(struct kobject *kobj, const struct attribute *attr, const void *ns = NULL; int err; + if (!dir_sd) { + WARN(1, KERN_ERR "sysfs: kobject %s without dirent\n", + kobject_name(kobj)); + return -ENOENT; + } + err = 0; if (!sysfs_ns_type(dir_sd)) goto out; diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c index c81b22f3ace..deb804bec9d 100644 --- a/fs/sysfs/inode.c +++ b/fs/sysfs/inode.c @@ -318,8 +318,11 @@ int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const void *ns, const cha struct sysfs_addrm_cxt acxt; struct sysfs_dirent *sd; - if (!dir_sd) + if (!dir_sd) { + WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n", + name); return -ENOENT; + } sysfs_addrm_start(&acxt, dir_sd); -- 2.11.4.GIT