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| author | Tyler Hicks <tyhicks@linux.vnet.ibm.com> | 2009-10-07 17:35:46 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-10-12 11:33:06 -0700 |
| commit | da40cf167d517e0f2cdd79a0d0590482a8532585 (patch) | |
| tree | 1294ea00408a06767842be4275546c538e26f545 | |
| parent | 329e7f58ae607c2dccc7e523e56c60d373dc6e4b (diff) | |
| download | kernel-common-da40cf167d517e0f2cdd79a0d0590482a8532585.tar.gz kernel-common-da40cf167d517e0f2cdd79a0d0590482a8532585.tar.bz2 kernel-common-da40cf167d517e0f2cdd79a0d0590482a8532585.zip | |
eCryptfs: Prevent lower dentry from going negative during unlink (CVE-2009-2908)
commit 9c2d2056647790c5034d722bd24e9d913ebca73c upstream.
When calling vfs_unlink() on the lower dentry, d_delete() turns the
dentry into a negative dentry when the d_count is 1. This eventually
caused a NULL pointer deref when a read() or write() was done and the
negative dentry's d_inode was dereferenced in
ecryptfs_read_update_atime() or ecryptfs_getxattr().
Placing mutt's tmpdir in an eCryptfs mount is what initially triggered
the oops and I was able to reproduce it with the following sequence:
open("/tmp/upper/foo", O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW, 0600) = 3
link("/tmp/upper/foo", "/tmp/upper/bar") = 0
unlink("/tmp/upper/foo") = 0
open("/tmp/upper/bar", O_RDWR|O_CREAT|O_NOFOLLOW, 0600) = 4
unlink("/tmp/upper/bar") = 0
write(4, "eCryptfs test\n"..., 14 <unfinished ...>
+++ killed by SIGKILL +++
https://bugs.launchpad.net/ecryptfs/+bug/387073
Reported-by: Loïc Minier <loic.minier@canonical.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: ecryptfs-devel@lists.launchpad.net
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | fs/ecryptfs/inode.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c index 5e78fc179886..1c1220e4aff0 100644 --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -443,6 +443,7 @@ static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry) struct inode *lower_dir_inode = ecryptfs_inode_to_lower(dir); struct dentry *lower_dir_dentry; + dget(lower_dentry); lower_dir_dentry = lock_parent(lower_dentry); rc = vfs_unlink(lower_dir_inode, lower_dentry); if (rc) { @@ -456,6 +457,7 @@ static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry) d_drop(dentry); out_unlock: unlock_dir(lower_dir_dentry); + dput(lower_dentry); return rc; } |