[PATCH -next] bcachefs: fix possible null-ptr-deref in __bch2_ec_stripe_head_get()

[Gaosheng Cui]

The function ec_new_stripe_head_alloc() returns nullptr if kzalloc()
fails. It is crucial to verify its return value before dereferencing
it to avoid a potential nullptr dereference.

Fixes: 035d72f72c91 ("bcachefs: bch2_ec_stripe_head_get() now checks for change 
in rw devices")
Signed-off-by: Gaosheng Cui <cuigaoshe...@huawei.com>
---
 fs/bcachefs/ec.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/bcachefs/ec.c b/fs/bcachefs/ec.c
index 25d20f73df60..b24089733467 100644
--- a/fs/bcachefs/ec.c
+++ b/fs/bcachefs/ec.c
@@ -1859,6 +1859,10 @@ __bch2_ec_stripe_head_get(struct btree_trans *trans,
                }
 
        h = ec_new_stripe_head_alloc(c, disk_label, algo, redundancy, 
watermark);
+       if (!h) {
+               h = ERR_PTR(-ENOMEM);
+               goto err;
+       }
 found:
        if (h->rw_devs_change_count != c->rw_devs_change_count)
                ec_stripe_head_devs_update(c, h);
-- 
2.25.1