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authorAlexander Viro <aviro@redhat.com>2006-01-14 15:29:55 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2006-01-30 22:13:17 -0800
commit1518d0b7a1ab6465487491c374bd18df6a4c036b (patch)
tree164ce6aca1622cd7761e8c964b5a89f5b1516384
parentad9ed6ca1b9f075a668a54c85ca5e706c19427a1 (diff)
downloadlinux-linaro-stable-1518d0b7a1ab6465487491c374bd18df6a4c036b.tar.gz
[PATCH] Fix double decrement of mqueue_mnt->mnt_count in sys_mq_open (CVE-2005-3356)
Fixed the refcounting on failure exits in sys_mq_open() and cleaned the logics up. Rules are actually pretty simple - dentry_open() expects vfsmount and dentry to be pinned down and it either transfers them into created struct file or drops them. Old code had been very confused in that area - if dentry_open() had failed either in do_open() or do_create(), we ended up dentry and mqueue_mnt dropped twice, once by dentry_open() cleanup and then by sys_mq_open(). Fix consists of making the rules for do_create() and do_open() same as for dentry_open() and updating the sys_mq_open() accordingly; that actually leads to more straightforward code and less work on normal path. Signed-off-by: Al Viro <aviro@redhat.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--ipc/mqueue.c59
1 files changed, 33 insertions, 26 deletions
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index c8943b53d8e6..565b2fa88d49 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -598,15 +598,16 @@ static int mq_attr_ok(struct mq_attr *attr)
static struct file *do_create(struct dentry *dir, struct dentry *dentry,
int oflag, mode_t mode, struct mq_attr __user *u_attr)
{
- struct file *filp;
struct mq_attr attr;
int ret;
- if (u_attr != NULL) {
+ if (u_attr) {
+ ret = -EFAULT;
if (copy_from_user(&attr, u_attr, sizeof(attr)))
- return ERR_PTR(-EFAULT);
+ goto out;
+ ret = -EINVAL;
if (!mq_attr_ok(&attr))
- return ERR_PTR(-EINVAL);
+ goto out;
/* store for use during create */
dentry->d_fsdata = &attr;
}
@@ -615,13 +616,14 @@ static struct file *do_create(struct dentry *dir, struct dentry *dentry,
ret = vfs_create(dir->d_inode, dentry, mode, NULL);
dentry->d_fsdata = NULL;
if (ret)
- return ERR_PTR(ret);
+ goto out;
- filp = dentry_open(dentry, mqueue_mnt, oflag);
- if (!IS_ERR(filp))
- dget(dentry);
+ return dentry_open(dentry, mqueue_mnt, oflag);
- return filp;
+out:
+ dput(dentry);
+ mntput(mqueue_mnt);
+ return ERR_PTR(ret);
}
/* Opens existing queue */
@@ -629,20 +631,20 @@ static struct file *do_open(struct dentry *dentry, int oflag)
{
static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
MAY_READ | MAY_WRITE };
- struct file *filp;
- if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
+ if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
+ dput(dentry);
+ mntput(mqueue_mnt);
return ERR_PTR(-EINVAL);
+ }
- if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL))
+ if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
+ dput(dentry);
+ mntput(mqueue_mnt);
return ERR_PTR(-EACCES);
+ }
- filp = dentry_open(dentry, mqueue_mnt, oflag);
-
- if (!IS_ERR(filp))
- dget(dentry);
-
- return filp;
+ return dentry_open(dentry, mqueue_mnt, oflag);
}
asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
@@ -670,17 +672,20 @@ asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
if (oflag & O_CREAT) {
if (dentry->d_inode) { /* entry already exists */
- filp = (oflag & O_EXCL) ? ERR_PTR(-EEXIST) :
- do_open(dentry, oflag);
+ error = -EEXIST;
+ if (oflag & O_EXCL)
+ goto out;
+ filp = do_open(dentry, oflag);
} else {
filp = do_create(mqueue_mnt->mnt_root, dentry,
oflag, mode, u_attr);
}
- } else
- filp = (dentry->d_inode) ? do_open(dentry, oflag) :
- ERR_PTR(-ENOENT);
-
- dput(dentry);
+ } else {
+ error = -ENOENT;
+ if (!dentry->d_inode)
+ goto out;
+ filp = do_open(dentry, oflag);
+ }
if (IS_ERR(filp)) {
error = PTR_ERR(filp);
@@ -691,8 +696,10 @@ asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
fd_install(fd, filp);
goto out_upsem;
-out_putfd:
+out:
+ dput(dentry);
mntput(mqueue_mnt);
+out_putfd:
put_unused_fd(fd);
out_err:
fd = error;