[PATCH] bcache: revert replacing IS_ERR_OR_NULL with IS_ERR

[Markus Weippert <markus@xxxxxxxxxxxx>]

Commit 028ddcac477b ("bcache: Remove unnecessary NULL point check in
node allocations") replaced IS_ERR_OR_NULL by IS_ERR. This leads to a
NULL pointer dereference.

BUG: kernel NULL pointer dereference, address: 0000000000000080
Call Trace:
 ? __die_body.cold+0x1a/0x1f
 ? page_fault_oops+0xd2/0x2b0
 ? exc_page_fault+0x70/0x170
 ? asm_exc_page_fault+0x22/0x30
 ? btree_node_free+0xf/0x160 [bcache]
 ? up_write+0x32/0x60
 btree_gc_coalesce+0x2aa/0x890 [bcache]
 ? bch_extent_bad+0x70/0x170 [bcache]
 btree_gc_recurse+0x130/0x390 [bcache]
 ? btree_gc_mark_node+0x72/0x230 [bcache]
 bch_btree_gc+0x5da/0x600 [bcache]
 ? cpuusage_read+0x10/0x10
 ? bch_btree_gc+0x600/0x600 [bcache]
 bch_gc_thread+0x135/0x180 [bcache]

The relevant code starts with:

    new_nodes[0] = NULL;

    for (i = 0; i < nodes; i++) {
        if (__bch_keylist_realloc(&keylist, bkey_u64s(&r[i].b->key)))
            goto out_nocoalesce;
    // ...
out_nocoalesce:
    // ...
    for (i = 0; i < nodes; i++)
        if (!IS_ERR(new_nodes[i])) {  // IS_ERR_OR_NULL before
028ddcac477b
            btree_node_free(new_nodes[i]);  // new_nodes[0] is NULL
            rw_unlock(true, new_nodes[i]);
        }

This patch replaces IS_ERR() by IS_ERR_OR_NULL() to fix this.

Fixes: 028ddcac477b ("bcache: Remove unnecessary NULL point check in
node allocations")
Link:
https://lore.kernel.org/all/3DF4A87A-2AC1-4893-AE5F-E921478419A9@xxxxxxx/
Cc: stable@xxxxxxxxxxxxxxx
Cc: Zheng Wang <zyytlz.wz@xxxxxxx>
Cc: Coly Li <colyli@xxxxxxx>
Signed-off-by: Markus Weippert <markus@xxxxxxxxxxxx>

---
 drivers/md/bcache/btree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index de3019972..261596791 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -1522,7 +1522,7 @@ static int btree_gc_coalesce(struct btree *b,
struct btree_op *op,
        bch_keylist_free(&keylist);
 
        for (i = 0; i < nodes; i++)
-               if (!IS_ERR(new_nodes[i])) {
+               if (!IS_ERR_OR_NULL(new_nodes[i])) {
                        btree_node_free(new_nodes[i]);
                        rw_unlock(true, new_nodes[i]);
                }
--