Discussion:
[PATCH] jffs2: ensure wbuf_verify is valid before using it.
(too old to reply)
Hou Tao
2018-10-20 12:08:49 UTC
Permalink
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: ***@vger.kernel.org
Fixes: 0029da3bf430 ("JFFS2: add UBI support")
Signed-off-by: Hou Tao <***@huawei.com>
---
fs/jffs2/wbuf.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/fs/jffs2/wbuf.c b/fs/jffs2/wbuf.c
index c6821a509481..3de45f4559d1 100644
--- a/fs/jffs2/wbuf.c
+++ b/fs/jffs2/wbuf.c
@@ -234,6 +234,13 @@ static int jffs2_verify_write(struct jffs2_sb_info *c, unsigned char *buf,
size_t retlen;
char *eccstr;

+ /*
+ * MTD emulated by UBI volume doesn't allocate wbuf_verify,
+ * because it can do the verification itself.
+ */
+ if (!c->wbuf_verify)
+ return 0;
+
ret = mtd_read(c->mtd, ofs, c->wbuf_pagesize, &retlen, c->wbuf_verify);
if (ret && ret != -EUCLEAN && ret != -EBADMSG) {
pr_warn("%s(): Read back of page at %08x failed: %d\n",
--
2.16.2.dirty
Hou Tao
2018-12-09 06:35:08 UTC
Permalink
ping ?
Post by Hou Tao
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
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
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().
Fixes: 0029da3bf430 ("JFFS2: add UBI support")
---
fs/jffs2/wbuf.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/fs/jffs2/wbuf.c b/fs/jffs2/wbuf.c
index c6821a509481..3de45f4559d1 100644
--- a/fs/jffs2/wbuf.c
+++ b/fs/jffs2/wbuf.c
@@ -234,6 +234,13 @@ static int jffs2_verify_write(struct jffs2_sb_info *c, unsigned char *buf,
size_t retlen;
char *eccstr;
+ /*
+ * MTD emulated by UBI volume doesn't allocate wbuf_verify,
+ * because it can do the verification itself.
+ */
+ if (!c->wbuf_verify)
+ return 0;
+
ret = mtd_read(c->mtd, ofs, c->wbuf_pagesize, &retlen, c->wbuf_verify);
if (ret && ret != -EUCLEAN && ret != -EBADMSG) {
pr_warn("%s(): Read back of page at %08x failed: %d\n",
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