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Date: Wed, 01 Feb 2012 13:00:00 -0800 From: Greg KH <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org Cc: torvalds@...ux-foundation.org, akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk, "Eric W. Biederman" <ebiederm@...ssion.com>, Wolfgang Frisch <wfpub@...mbden.net> Subject: [36/89] sysfs: Complain bitterly about attempts to remove files from nonexistent directories. 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Eric W. Biederman" <ebiederm@...ssion.com> 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 <ebiederm@...ssion.com> Reported-by: Wolfgang Frisch <wfpub@...mbden.net> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- fs/sysfs/file.c | 6 ++++++ fs/sysfs/inode.c | 5 ++++- 2 files changed, 10 insertions(+), 1 deletion(-) --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -493,6 +493,12 @@ int sysfs_attr_ns(struct kobject *kobj, 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; --- a/fs/sysfs/inode.c +++ b/fs/sysfs/inode.c @@ -318,8 +318,11 @@ int sysfs_hash_and_remove(struct sysfs_d 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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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