mtd: Fix gluebi NULL pointer dereference caused by ftl notifier

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: mtd: Fix gluebi NULL pointer dereference caused by ftl notifier If both ftl.ko and gluebi.ko are loaded, the notifier of ftl triggers NULL pointer dereference when trying to access ‘gluebi->desc’ in gluebi_read(). ubi_gluebi_init ubi_register_volume_notifier ubi_enumerate_volumes ubi_notify_all gluebi_notify nb->notifier_call() gluebi_create mtd_device_register mtd_device_parse_register add_mtd_device blktrans_notify_add not->add() ftl_add_mtd tr->add_mtd() scan_header mtd_read mtd_read_oob mtd_read_oob_std gluebi_read mtd->read() gluebi->desc - NULL Detailed reproduction information available at the Link [1], In the normal case, obtain gluebi->desc in the gluebi_get_device(), and access gluebi->desc in the gluebi_read(). However, gluebi_get_device() is not executed in advance in the ftl_add_mtd() process, which leads to NULL pointer dereference. The solution for the gluebi module is to run jffs2 on the UBI volume without considering working with ftl or mtdblock [2]. Therefore, this problem can be avoided by preventing gluebi from creating the mtdblock device after creating mtd partition of the type MTD_UBIVOLUME.

References

• https://git.kernel.org/stable/c/aeba358bcc8ffddf9b4a9bd0e5ec9eb338d46022
• https://git.kernel.org/stable/c/1bf4fe14e97cda621522eb2f28b0a4e87c5b0745
• https://git.kernel.org/stable/c/001a3f59d8c914ef8273461d4bf495df384cc5f8
• https://git.kernel.org/stable/c/d8ac2537763b54d278b80b2b080e1652523c7d4c
• https://git.kernel.org/stable/c/5389407bba1eab1266c6d83e226fb0840cb98dd5
• https://git.kernel.org/stable/c/cfd7c9d260dc0a3baaea05a122a19ab91e193c65
• https://git.kernel.org/stable/c/b36aaa64d58aaa2f2cbc8275e89bae76a2b6c3dc
• https://git.kernel.org/stable/c/a43bdc376deab5fff1ceb93dca55bcab8dbdc1d6