Messages in this thread | | | Subject | Re: [Ocfs2-devel] [PATCH 1/3 v2] fs: ocfs2: Fix possible null-pointer dereferences in ocfs2_xa_prepare_entry() | From | Changwei Ge <> | Date | Mon, 5 Aug 2019 11:08:20 +0800 |
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Hi Jia-Ju,
Please checkout my comments inline.
On 2019/7/27 8:49 上午, Joseph Qi wrote: > > 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);
This won't deference a NULL ->xl_entry because ->xlo_add_entry() is already called to whether ocfs2_xa_block_add_entry() or ocfs2_xa_bucket_add_entry()
From the function name we can tell the intention it wants to add entry so of course it should be NULL before calling it.
Thanks,
Changwei
>> 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 >> > _______________________________________________ > Ocfs2-devel mailing list > Ocfs2-devel@oss.oracle.com > https://oss.oracle.com/mailman/listinfo/ocfs2-devel
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