From: Bob Peterson rpeterso@redhat.com
commit fe5e7ba11fcf1d75af8173836309e8562aefedef upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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(-)
--- a/fs/gfs2/log.c +++ b/fs/gfs2/log.c @@ -609,6 +609,14 @@ void gfs2_add_revoke(struct gfs2_sbd *sd 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; --- a/fs/gfs2/log.h +++ b/fs/gfs2/log.h @@ -77,6 +77,7 @@ extern void gfs2_ail1_flush(struct gfs2_ extern void gfs2_log_shutdown(struct gfs2_sbd *sdp); 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__ */ --- a/fs/gfs2/lops.c +++ b/fs/gfs2/lops.c @@ -882,10 +882,7 @@ static void revoke_lo_after_commit(struc 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); } } --- a/fs/gfs2/trans.c +++ b/fs/gfs2/trans.c @@ -262,6 +262,8 @@ void gfs2_trans_remove_revoke(struct gfs 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)