Messages in this thread |  | | Subject | Re: [PATCH 1/3 v2] fs: ocfs2: Fix possible null-pointer dereferences in ocfs2_xa_prepare_entry() | From | Joseph Qi <> | Date | Sat, 27 Jul 2019 08:49:57 +0800 |
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On 19/7/26 18:14, Jia-Ju Bai wrote: > In ocfs2_xa_prepare_entry(), there is an if statement on line 2136 to > check whether loc->xl_entry is NULL: > if (loc->xl_entry) > > When loc->xl_entry is NULL, it is used on line 2158: > ocfs2_xa_add_entry(loc, name_hash); > loc->xl_entry->xe_name_hash = cpu_to_le32(name_hash); > loc->xl_entry->xe_name_offset = cpu_to_le16(loc->xl_size); > and line 2164: > ocfs2_xa_add_namevalue(loc, xi); > loc->xl_entry->xe_value_size = cpu_to_le64(xi->xi_value_len); > loc->xl_entry->xe_name_len = xi->xi_name_len; > > Thus, possible null-pointer dereferences may occur. > > To fix these bugs, if loc-xl_entry is NULL, ocfs2_xa_prepare_entry() > abnormally returns with -EINVAL. > > These bugs are found by a static analysis tool STCheck written by us. > > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com> > --- > v2: > * Directly return -EINVAL if loc-xl_entry is NULL. > Thank Joseph for helpful advice. > > --- > fs/ocfs2/xattr.c | 44 +++++++++++++++++++++++--------------------- > 1 file changed, 23 insertions(+), 21 deletions(-) > > diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c > index 385f3aaa2448..4b876c82a35c 100644 > --- a/fs/ocfs2/xattr.c > +++ b/fs/ocfs2/xattr.c > @@ -2133,29 +2133,31 @@ static int ocfs2_xa_prepare_entry(struct ocfs2_xa_loc *loc, > if (rc) > goto out; > > - if (loc->xl_entry) { > - if (ocfs2_xa_can_reuse_entry(loc, xi)) { > - orig_value_size = loc->xl_entry->xe_value_size; > - rc = ocfs2_xa_reuse_entry(loc, xi, ctxt); > - if (rc) > - goto out; > - goto alloc_value; > - } > + if (!loc->xl_entry) { > + rc = -EINVAL; > + goto out; > + } > > - if (!ocfs2_xattr_is_local(loc->xl_entry)) { > - orig_clusters = ocfs2_xa_value_clusters(loc); > - rc = ocfs2_xa_value_truncate(loc, 0, ctxt); > - if (rc) { > - mlog_errno(rc); > - ocfs2_xa_cleanup_value_truncate(loc, > - "overwriting", > - orig_clusters); > - goto out; > - } > + if (ocfs2_xa_can_reuse_entry(loc, xi)) { > + orig_value_size = loc->xl_entry->xe_value_size; > + rc = ocfs2_xa_reuse_entry(loc, xi, ctxt); > + if (rc) > + goto out; > + goto alloc_value; > + } > + > + if (!ocfs2_xattr_is_local(loc->xl_entry)) { > + orig_clusters = ocfs2_xa_value_clusters(loc); > + rc = ocfs2_xa_value_truncate(loc, 0, ctxt); > + if (rc) { > + mlog_errno(rc); > + ocfs2_xa_cleanup_value_truncate(loc, > + "overwriting", > + orig_clusters); > + goto out; > } > - ocfs2_xa_wipe_namevalue(loc); > - } else > - ocfs2_xa_add_entry(loc, name_hash); > + } > + ocfs2_xa_wipe_namevalue(loc); > > /* > * If we get here, we have a blank entry. Fill it. We grow our >
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