CVE-2024-26689

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ceph: prevent use-after-free in encode_cap_msg()<br /> <br /> In fs/ceph/caps.c, in encode_cap_msg(), "use after free" error was<br /> caught by KASAN at this line - &amp;#39;ceph_buffer_get(arg-&gt;xattr_buf);&amp;#39;. This<br /> implies before the refcount could be increment here, it was freed.<br /> <br /> In same file, in "handle_cap_grant()" refcount is decremented by this<br /> line - &amp;#39;ceph_buffer_put(ci-&gt;i_xattrs.blob);&amp;#39;. It appears that a race<br /> occurred and resource was freed by the latter line before the former<br /> line could increment it.<br /> <br /> encode_cap_msg() is called by __send_cap() and __send_cap() is called by<br /> ceph_check_caps() after calling __prep_cap(). __prep_cap() is where<br /> arg-&gt;xattr_buf is assigned to ci-&gt;i_xattrs.blob. This is the spot where<br /> the refcount must be increased to prevent "use after free" error.