From: Bob Peterson rpeterso@redhat.com

Commit 9287c6452d2b fixed a situation in which gfs2 could use a glock after it had been freed. To do that, it temporarily added a new glock reference by calling gfs2_glock_hold in function gfs2_add_revoke. However, if the bd element was removed by gfs2_trans_remove_revoke, it failed to drop the additional reference.

This patch adds logic to gfs2_trans_remove_revoke to properly drop the additional glock reference.

Fixes: 9287c6452d2b ("gfs2: Fix occasional glock use-after-free") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Bob Peterson rpeterso@redhat.com Signed-off-by: Andreas Gruenbacher agruenba@redhat.com --- fs/gfs2/log.c | 8 ++++++++ fs/gfs2/log.h | 1 + fs/gfs2/lops.c | 5 +---- fs/gfs2/trans.c | 2 ++ 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c index 4a7713c62f04..68af71eb28c6 100644 --- a/fs/gfs2/log.c +++ b/fs/gfs2/log.c @@ -611,6 +611,14 @@ void gfs2_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd) list_add(&bd->bd_list, &sdp->sd_log_revokes); }

+void gfs2_glock_remove_revoke(struct gfs2_glock *gl) +{ + if (atomic_dec_return(&gl->gl_revokes) == 0) { + clear_bit(GLF_LFLUSH, &gl->gl_flags); + gfs2_glock_queue_put(gl); + } +} + void gfs2_write_revokes(struct gfs2_sbd *sdp) { struct gfs2_trans *tr; diff --git a/fs/gfs2/log.h b/fs/gfs2/log.h index 2421181dbfb9..2ff163a8dce1 100644 --- a/fs/gfs2/log.h +++ b/fs/gfs2/log.h @@ -76,6 +76,7 @@ extern void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc)

extern int gfs2_logd(void *data); extern void gfs2_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd); +extern void gfs2_glock_remove_revoke(struct gfs2_glock *gl); extern void gfs2_write_revokes(struct gfs2_sbd *sdp);

#endif /* __LOG_DOT_H__ */ diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c index 313b83ef6657..55fed7daf2b1 100644 --- a/fs/gfs2/lops.c +++ b/fs/gfs2/lops.c @@ -883,10 +883,7 @@ static void revoke_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr) bd = list_entry(head->next, struct gfs2_bufdata, bd_list); list_del_init(&bd->bd_list); gl = bd->bd_gl; - if (atomic_dec_return(&gl->gl_revokes) == 0) { - clear_bit(GLF_LFLUSH, &gl->gl_flags); - gfs2_glock_queue_put(gl); - } + gfs2_glock_remove_revoke(gl); kmem_cache_free(gfs2_bufdata_cachep, bd); } } diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c index 35e3059255fe..9d4227330de4 100644 --- a/fs/gfs2/trans.c +++ b/fs/gfs2/trans.c @@ -262,6 +262,8 @@ void gfs2_trans_remove_revoke(struct gfs2_sbd *sdp, u64 blkno, unsigned int len) list_del_init(&bd->bd_list); gfs2_assert_withdraw(sdp, sdp->sd_log_num_revoke); sdp->sd_log_num_revoke--; + if (bd->bd_gl) + gfs2_glock_remove_revoke(bd->bd_gl); kmem_cache_free(gfs2_bufdata_cachep, bd); tr->tr_num_revoke--; if (--n == 0)