Commit 56e94ea1 authored Oct 06, 2019 by Jia-Ju Bai Committed by Linus Torvalds Oct 07, 2019

fs: ocfs2: fix possible null-pointer dereferences in ocfs2_xa_prepare_entry()

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.

[akpm@linux-foundation.org: remove now-unused ocfs2_xa_add_entry()]
Link: http://lkml.kernel.org/r/20190726101447.9153-1-baijiaju1990@gmail.com


Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7a243c82

fs/ocfs2/xattr.c

+23 −33

Original line number	Diff line number	Diff line
		@@ -1490,18 +1490,6 @@ static int ocfs2_xa_check_space(struct ocfs2_xa_loc *loc,
		return loc->xl_ops->xlo_check_space(loc, xi);
		}

		static void ocfs2_xa_add_entry(struct ocfs2_xa_loc *loc, u32 name_hash)
		{
		loc->xl_ops->xlo_add_entry(loc, name_hash);
		loc->xl_entry->xe_name_hash = cpu_to_le32(name_hash);
		/*
		* We can't leave the new entry's xe_name_offset at zero or
		* add_namevalue() will go nuts. We set it to the size of our
		* storage so that it can never be less than any other entry.
		*/
		loc->xl_entry->xe_name_offset = cpu_to_le16(loc->xl_size);
		}

		static void ocfs2_xa_add_namevalue(struct ocfs2_xa_loc *loc,
		struct ocfs2_xattr_info *xi)
		{
		@@ -2133,7 +2121,11 @@ static int ocfs2_xa_prepare_entry(struct ocfs2_xa_loc *loc,
		if (rc)
		goto out;

		if (loc->xl_entry) {
		if (!loc->xl_entry) {
		rc = -EINVAL;
		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);
		@@ -2154,8 +2146,6 @@ static int ocfs2_xa_prepare_entry(struct ocfs2_xa_loc *loc,
		}
		}
		ocfs2_xa_wipe_namevalue(loc);
		} else
		ocfs2_xa_add_entry(loc, name_hash);

		/*
		* If we get here, we have a blank entry. Fill it. We grow our