Re: [PATCH] jffs2: ensure wbuf_verify is valid before using it.

On Sat, Oct 20, 2018 at 2:06 PM Hou Tao houtao1@huawei.com wrote:

Now MTD emulated by UBI volumn doesn't allocate wbuf_verify in jffs2_ubivol_setup(), because UBI can do the verifcation itself, so when CONFIG_JFFS2_FS_WBUF_VERIFY is enabled and a MTD device emulated by UBI volumn is used, a Oops will occur as show in the following trace:

general protection fault: 0000 [#1] SMP KASAN PTI
CPU: 6 PID: 404 Comm: kworker/6:1 Not tainted 4.19.0-rc8
Workqueue: events_long delayed_wbuf_sync
RIP: 0010:ubi_io_read+0x156/0x650
Call Trace:
 ubi_eba_read_leb+0x57d/0xba0
 ubi_leb_read+0xe5/0x1b0
 gluebi_read+0x10c/0x1a0
 mtd_read+0x112/0x340
 jffs2_verify_write+0xef/0x440
 __jffs2_flush_wbuf+0x3fa/0x3540
 jffs2_flush_wbuf_gc+0x1b1/0x2e0
 process_one_work+0x58b/0x11e0
 worker_thread+0x8f/0xfe0
 kthread+0x2ae/0x3a0
 ret_from_fork+0x35/0x40

Fix the problem by checking the validity of wbuf_verify before using it in jffs2_verify_write().

Cc: stable@vger.kernel.org Fixes: 0029da3bf430 ("JFFS2: add UBI support") Signed-off-by: Hou Tao houtao1@huawei.com

Reviewed-by: Richard Weinberger richard@nod.at

BTW: Are you actually using glubi? It is on my list of things I'd like to kill. :-)