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gfs2: Fix NULL pointer dereference in gfs2_log_flush

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In gfs2_jindex_free(), set sdp->sd_jdesc to NULL under the log flush
lock to provide exclusion against gfs2_log_flush().

In gfs2_log_flush(), check if sdp->sd_jdesc is non-NULL before
dereferencing it.  Otherwise, we could run into a NULL pointer
dereference when outstanding glock work races with an unmount
(glock_work_func -> run_queue -> do_xmote -> inode_go_sync ->
gfs2_log_flush).

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2024-03-11 15:51:59 +01:00
parent b01189333e
commit 35264909e9
2 changed files with 6 additions and 1 deletions
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1
fs/gfs2/log.c
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@ -1108,6 +1108,7 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags)
lops_before_commit(sdp, tr); lops_before_commit(sdp, tr);
if (gfs2_withdrawing_or_withdrawn(sdp)) if (gfs2_withdrawing_or_withdrawn(sdp))
goto out_withdraw; goto out_withdraw;
if (sdp->sd_jdesc)
gfs2_log_submit_bio(&sdp->sd_jdesc->jd_log_bio, REQ_OP_WRITE); gfs2_log_submit_bio(&sdp->sd_jdesc->jd_log_bio, REQ_OP_WRITE);
if (gfs2_withdrawing_or_withdrawn(sdp)) if (gfs2_withdrawing_or_withdrawn(sdp))
goto out_withdraw; goto out_withdraw;

4
fs/gfs2/super.c
View File

@ -67,9 +67,13 @@ void gfs2_jindex_free(struct gfs2_sbd *sdp)
sdp->sd_journals = 0; sdp->sd_journals = 0;
spin_unlock(&sdp->sd_jindex_spin); spin_unlock(&sdp->sd_jindex_spin);
down_write(&sdp->sd_log_flush_lock);
sdp->sd_jdesc = NULL; sdp->sd_jdesc = NULL;
up_write(&sdp->sd_log_flush_lock);
while (!list_empty(&list)) { while (!list_empty(&list)) {
jd = list_first_entry(&list, struct gfs2_jdesc, jd_list); jd = list_first_entry(&list, struct gfs2_jdesc, jd_list);
BUG_ON(jd->jd_log_bio);
gfs2_free_journal_extents(jd); gfs2_free_journal_extents(jd);
list_del(&jd->jd_list); list_del(&jd->jd_list);
iput(jd->jd_inode); iput(jd->jd_inode);