When the gfs2_logd daemon withdrew, the withdraw sequence called
into make_fs_ro() to make the file system read-only. That caused the
journal descriptors to be freed. However, those journal descriptors
were used by gfs2_logd's call to gfs2_ail_flush_reqd(). This caused
a use-after free and NULL pointer dereference.
This patch changes function gfs2_logd() so that it stops all logd
work until the thread is told to stop. Once a withdraw is done,
it only does an interruptible sleep.
Signed-off-by: Bob Peterson <rpete...@redhat.com>
---
fs/gfs2/log.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 3a75843ae580..cf0b80c78c82 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -1131,6 +1131,10 @@ int gfs2_logd(void *data)
while (!kthread_should_stop()) {
+ if (gfs2_withdrawn(sdp)) {
+ msleep_interruptible(HZ);
+ continue;
+ }
/* Check for errors writing to the journal */
if (sdp->sd_log_error) {
gfs2_lm(sdp,
@@ -1139,6 +1143,7 @@ int gfs2_logd(void *data)
"prevent further damage.\n",
sdp->sd_fsname, sdp->sd_log_error);
gfs2_withdraw(sdp);
+ continue;
}
did_flush = false;
--
2.25.1
