From d22f69a08dcb0f469170cda1976d5938cb0e5dcf Mon Sep 17 00:00:00 2001 From: Bob Peterson Date: Fri, 24 Apr 2020 12:17:33 -0500 Subject: gfs2: Fix use-after-free in gfs2_logd after withdraw 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 Signed-off-by: Andreas Gruenbacher --- fs/gfs2/log.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'fs/gfs2') 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; -- cgit v1.2.3-70-g09d2