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SubjectRe: [LKP] [mtd] c4dfa25ab3: kernel_BUG_at_fs/sysfs/file.c
On Wed, Jan 02, 2019 at 10:44:50PM +0100, Rafael J. Wysocki wrote:
> On Wed, Jan 2, 2019 at 8:53 PM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>
> [cut]
>
> > Greg, Rafael: it does strike me that the "BUG_ON()" in
> > sysfs_create_file_ns() could easily have been a
> >
> > if (WARN_ON(..))
> > return -EINVAL;
> >
> > which would have made the machine boot and probably make things easier
> > for normal users to report. The kernel test robot doesn't care, but
> > non-booting kernels are usually not nice to debug or report for normal
> > human beings..
>
> I agree.
>
> This isn't a good enough reason to crash the kernel IMO.

I agree too.

Here's a patch for this, I'll queue it up after -rc1 is out. Rafael,
look good to you?

--------------

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [PATCH] sysfs: convert BUG_ON to WARN_ON

It's rude to crash the system just because the developer did something
wrong, as it prevents them from usually even seeing what went wrong.

So convert the few BUG_ON() calls that have snuck into the sysfs code
over the years to WARN_ON() to make it more "friendly". All of these
are able to be recovered from, so it makes no sense to crash.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/sysfs/dir.c | 3 ++-
fs/sysfs/file.c | 6 ++++--
fs/sysfs/group.c | 3 ++-
fs/sysfs/symlink.c | 3 ++-
4 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index feeae8081c22..aa85f2874a9f 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -43,7 +43,8 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
kuid_t uid;
kgid_t gid;

- BUG_ON(!kobj);
+ if (WARN_ON(!kobj))
+ return -EINVAL;

if (kobj->parent)
parent = kobj->parent->sd;
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index bb71db63c99c..51398457fe00 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -325,7 +325,8 @@ int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
kuid_t uid;
kgid_t gid;

- BUG_ON(!kobj || !kobj->sd || !attr);
+ if (WARN_ON(!kobj || !kobj->sd || !attr))
+ return -EINVAL;

kobject_get_ownership(kobj, &uid, &gid);
return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode,
@@ -537,7 +538,8 @@ int sysfs_create_bin_file(struct kobject *kobj,
kuid_t uid;
kgid_t gid;

- BUG_ON(!kobj || !kobj->sd || !attr);
+ if (WARN_ON(!kobj || !kobj->sd || !attr))
+ return -EINVAL;

kobject_get_ownership(kobj, &uid, &gid);
return sysfs_add_file_mode_ns(kobj->sd, &attr->attr, true,
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 1eb2d6307663..57038604d4a8 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -112,7 +112,8 @@ static int internal_create_group(struct kobject *kobj, int update,
kgid_t gid;
int error;

- BUG_ON(!kobj || (!update && !kobj->sd));
+ if (WARN_ON(!kobj || (!update && !kobj->sd)))
+ return -EINVAL;

/* Updates may happen before the object has been instantiated */
if (unlikely(update && !kobj->sd))
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 215c225b2ca1..c4deecc80f67 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -23,7 +23,8 @@ static int sysfs_do_create_link_sd(struct kernfs_node *parent,
{
struct kernfs_node *kn, *target = NULL;

- BUG_ON(!name || !parent);
+ if (WARN_ON(!name || !parent))
+ return -EINVAL;

/*
* We don't own @target_kobj and it may be removed at any time.
--
2.20.1
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