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| author | Tyler Hicks <tyhicks@linux.vnet.ibm.com> | 2009-09-22 12:52:17 -0500 |
|---|---|---|
| committer | Tyler Hicks <tyhicks@linux.vnet.ibm.com> | 2009-09-23 09:10:34 -0500 |
| commit | 9c2d2056647790c5034d722bd24e9d913ebca73c (patch) | |
| tree | 38db96956ac0167b2a277429746c500b522bc5aa /fs | |
| parent | 96a7b9c2f5df899f302ade45cf17ad753fe130fd (diff) | |
| download | linux-9c2d2056647790c5034d722bd24e9d913ebca73c.tar.gz linux-9c2d2056647790c5034d722bd24e9d913ebca73c.tar.bz2 linux-9c2d2056647790c5034d722bd24e9d913ebca73c.zip | |
eCryptfs: Prevent lower dentry from going negative during unlink
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
Cc: stable <stable@kernel.org>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Diffstat (limited to 'fs')
| -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 2f0945d63297..056fed62d0de 100644 --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -476,6 +476,7 @@ 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) { @@ -489,6 +490,7 @@ 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; } |