ext4: fix error pointer dereference in ext4_mb_load_buddy_gfp()

This code calls folio_put() on an error pointer which will lead to a
crash.  Check for both error pointers and NULL pointers before calling
folio_put().

Fixes: 5eea586b47f0 ("ext4: convert bd_buddy_page to bd_buddy_folio")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/eaafa1d9-a61c-4af4-9f97-d3ad72c60200@moroto.mountain
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 648989c125f2fefe98419f7528a92e5e3cce5c69..9dda9cd68ab2f5daf595957e4248e97229ec3ab8 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1717,7 +1717,7 @@ ext4_mb_load_buddy_gfp(struct super_block *sb, ext4_group_t group,
        return 0;
 
 err:
-       if (folio)
+       if (!IS_ERR_OR_NULL(folio))
                folio_put(folio);
        if (e4b->bd_bitmap_folio)
                folio_put(e4b->bd_bitmap_folio);