Re: [syzbot] [gfs2?] KASAN: slab-use-after-free Read in gfs2_invalidate_folio

[Edward Adam Davis]

please test uaf in gfs2_invalidate_folio

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git e8c39d0f57f3

diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
index 974aca9c8ea8..4ae5e73b6992 100644
--- a/fs/gfs2/aops.c
+++ b/fs/gfs2/aops.c
@@ -613,6 +613,7 @@ static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
 	gfs2_log_lock(sdp);
 	clear_buffer_dirty(bh);
 	bd = bh->b_private;
+	printk("bh: %p, bd: %p, %s\n", bh, bd, __func__);
 	if (bd) {
 		if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
 			list_del_init(&bd->bd_list);
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index aa1626955b2c..d9092692c2fe 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -78,7 +78,9 @@ static int gfs2_unstuffer_folio(struct gfs2_inode *ip, struct buffer_head *dibh,
 			map_bh(bh, inode->i_sb, block);
 
 		set_buffer_uptodate(bh);
+		printk("1.inode: %p, bh: %p, bd: %p, %s\n", ip, bh, bh->b_private, __func__);
 		gfs2_trans_add_data(ip->i_gl, bh);
+		printk("2.inode: %p, bh: %p, bd: %p, %s\n", ip, bh, bh->b_private, __func__);
 	} else {
 		folio_mark_dirty(folio);
 		gfs2_ordered_add_inode(ip);
@@ -105,6 +107,7 @@ static int __gfs2_unstuff_inode(struct gfs2_inode *ip, struct folio *folio)
 
 		unsigned int n = 1;
 		error = gfs2_alloc_blocks(ip, &block, &n, 0);
+		printk("1,inode: %p, n: %d, err: %d, %s\n", ip, n, error, __func__);
 		if (error)
 			goto out_brelse;
 		if (isdir) {
@@ -117,6 +120,7 @@ static int __gfs2_unstuff_inode(struct gfs2_inode *ip, struct folio *folio)
 			brelse(bh);
 		} else {
 			error = gfs2_unstuffer_folio(ip, dibh, block, folio);
+			printk("2,inode: %p, n: %d, err: %d, %s\n", ip, n, error, __func__);
 			if (error)
 				goto out_brelse;
 		}
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 8cddf955ebc0..6a65e7f5991a 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -1007,6 +1007,7 @@ static void trans_drain(struct gfs2_trans *tr)
 {
 	struct gfs2_bufdata *bd;
 	struct list_head *head;
+	struct buffer_head *bh;
 
 	if (!tr)
 		return;
@@ -1022,6 +1023,8 @@ static void trans_drain(struct gfs2_trans *tr)
 	head = &tr->tr_databuf;
 	while (!list_empty(head)) {
 		bd = list_first_entry(head, struct gfs2_bufdata, bd_list);
+		bh = container_of((void *)bd, struct buffer_head, b_private);
+		printk("bh: %p, bd: %p, %s\n", bh, bd, __func__);
 		list_del_init(&bd->bd_list);
 		if (!list_empty(&bd->bd_ail_st_list))
 			gfs2_remove_from_ail(bd);
diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index aa9cf0102848..3f18b066cc0d 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -1007,6 +1007,7 @@ static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda)
 		gfs2_glock_dq_uninit(&ghs[qx]);
 	inode_unlock(&ip->i_inode);
 	kfree(ghs);
+	printk("err: %d, %s\n", error, __func__);
 	gfs2_log_flush(ip->i_gl->gl_name.ln_sbd, ip->i_gl,
 		       GFS2_LOG_HEAD_FLUSH_NORMAL | GFS2_LFC_DO_SYNC);
 	if (!error) {
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 26d6c1eea559..2b291270817c 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -2236,7 +2236,9 @@ static void gfs2_alloc_extent(const struct gfs2_rbm *rbm, bool dinode,
 
 	*n = 1;
 	block = gfs2_rbm_to_block(rbm);
+	printk("1. bh: %p, bd: %p, %s\n", rbm_bi(rbm)->bi_bh, rbm_bi(rbm)->bi_bh->b_private, __func__);
 	gfs2_trans_add_meta(rbm->rgd->rd_gl, rbm_bi(rbm)->bi_bh);
+	printk("2. bh: %p, bd: %p, %s\n", rbm_bi(rbm)->bi_bh, rbm_bi(rbm)->bi_bh->b_private, __func__);
 	gfs2_setbit(rbm, true, dinode ? GFS2_BLKST_DINODE : GFS2_BLKST_USED);
 	block++;
 	while (*n < elen) {
diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
index 192213c7359a..d2353d052d34 100644
--- a/fs/gfs2/trans.c
+++ b/fs/gfs2/trans.c
@@ -205,10 +205,14 @@ void gfs2_trans_add_data(struct gfs2_glock *gl, struct buffer_head *bh)
 	if (bd == NULL) {
 		gfs2_log_unlock(sdp);
 		unlock_buffer(bh);
-		if (bh->b_private == NULL)
+		if (bh->b_private == NULL) {
 			bd = gfs2_alloc_bufdata(gl, bh);
-		else
+			printk("1bh: %p, bd: %p, %s\n", bh, bd, __func__);
+		}
+		else {
 			bd = bh->b_private;
+			printk("2bh: %p, bd: %p, %s\n", bh, bd, __func__);
+		}
 		lock_buffer(bh);
 		gfs2_log_lock(sdp);
 	}
@@ -247,10 +251,14 @@ void gfs2_trans_add_meta(struct gfs2_glock *gl, struct buffer_head *bh)
 		gfs2_log_unlock(sdp);
 		unlock_buffer(bh);
 		lock_page(bh->b_page);
-		if (bh->b_private == NULL)
+		if (bh->b_private == NULL) {
 			bd = gfs2_alloc_bufdata(gl, bh);
-		else
+			printk("1bh: %p, bd: %p, %s\n", bh, bd, __func__);
+		}
+		else {
 			bd = bh->b_private;
+			printk("2bh: %p, bd: %p, %s\n", bh, bd, __func__);
+		}
 		unlock_page(bh->b_page);
 		lock_buffer(bh);
 		gfs2_log_lock(sdp);