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Merge tag 'configfs-for-5.2-2' of git://git.infradead.org/users/hch/configfs

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Pull configs fix from Christoph Hellwig:

 - fix a use after free in configfs_d_iput (Sahitya Tummala)

* tag 'configfs-for-5.2-2' of git://git.infradead.org/users/hch/configfs:
  configfs: Fix use-after-free when accessing sd->s_dentry
This commit is contained in:
Linus Torvalds
2019-05-30 20:35:48 -07:00
parent c5ba171266 f6122ed2a4
commit 8cb7104d03
1 changed files with 6 additions and 8 deletions
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14
fs/configfs/dir.c
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@@ -58,15 +58,13 @@ static void configfs_d_iput(struct dentry * dentry,
if (sd) {
/* Coordinate with configfs_readdir */
spin_lock(&configfs_dirent_lock);
/* Coordinate with configfs_attach_attr where will increase
* sd->s_count and update sd->s_dentry to new allocated one.
* Only set sd->dentry to null when this dentry is the only
* sd owner.
* If not do so, configfs_d_iput may run just after
* configfs_attach_attr and set sd->s_dentry to null
* even it's still in use.
/*
* Set sd->s_dentry to null only when this dentry is the one
* that is going to be killed. Otherwise configfs_d_iput may
* run just after configfs_attach_attr and set sd->s_dentry to
* NULL even it's still in use.
*/
if (atomic_read(&sd->s_count) <= 2)
if (sd->s_dentry == dentry)
sd->s_dentry = NULL;
spin_unlock(&configfs_dirent_lock);