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Subject[PATCH 24/24] sysfs: In sysfs_add_one fail if the targe directory has been removed.
From: Eric W. Biederman <ebiederm@xmission.com>

If a bug in the upper layers results in someone attempting to add
to a sysfs directory that has already been removed, warn about it
and fail.

I don't believe this has ever happened, and it certainly never should
happen, but be strict to avoid errors creeping in.

Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
---
fs/sysfs/dir.c | 37 +++++++++++++++++++++++--------------
1 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 96f95f5..b75cb25 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -394,21 +394,17 @@ static char *sysfs_pathname(struct sysfs_dirent *sd, char *path)
int sysfs_add_one(struct sysfs_dirent *parent_sd, struct sysfs_dirent *sd)
{
struct iattr *ps_iattr;
+ char *path;
+ int result;

mutex_lock(&sysfs_mutex);
- if (sysfs_find_dirent(parent_sd, sd->s_name)) {
- char *path;
- mutex_unlock(&sysfs_mutex);

- path = kzalloc(PATH_MAX, GFP_KERNEL);
- WARN(1, KERN_WARNING
- "sysfs: cannot create duplicate filename '%s'\n",
- (path == NULL) ? sd->s_name :
- strcat(strcat(sysfs_pathname(parent_sd, path), "/"),
- sd->s_name));
- kfree(path);
- return -EEXIST;
- }
+ result = -ENOENT;
+ if (parent_sd->s_flags & SYSFS_FLAG_REMOVED)
+ goto out_err;
+
+ if (sysfs_find_dirent(parent_sd, sd->s_name))
+ goto out_err;

sd->s_parent = sysfs_get(parent_sd);
sysfs_link_sibling(sd);
@@ -417,9 +413,22 @@ int sysfs_add_one(struct sysfs_dirent *parent_sd, struct sysfs_dirent *sd)
ps_iattr = parent_sd->s_iattr;
if (ps_iattr)
ps_iattr->ia_ctime = ps_iattr->ia_mtime = CURRENT_TIME;
-
mutex_unlock(&sysfs_mutex);
return 0;
+
+out_err:
+ mutex_unlock(&sysfs_mutex);
+
+ path = kzalloc(PATH_MAX, GFP_KERNEL);
+ WARN(1, KERN_WARNING "sysfs: cannot create '%s' %s\n",
+ (path == NULL) ? sd->s_name :
+ strcat(strcat(sysfs_pathname(parent_sd, path), "/"),
+ sd->s_name),
+ (result == -EEXIST ? "duplicate filename" : "no such directory")
+ );
+ kfree(path);
+
+ return result;
}

/**
--
1.6.3.1.54.g99dd.dirty


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