From: Manas <[email protected]>

The syzkaller bug triggers BUG_ON assertions in
__bch2_dev_btree_bitmap_mark. btree_bitmap_shift is checked in
bch2_dev_btree_bitmap_marked_sectors prior to this. But only one out of
two assertions is checked. This patch adds the other as conditional.

Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=e8eff054face85d7ea41
Signed-off-by: Manas <[email protected]>
---
The syzkaller bug[1] triggers BUG_ON assertions in
__bch2_dev_btree_bitmap_mark.

btree_bitmap_shift is checked in bch2_dev_btree_bitmap_marked_sectors
prior to this. But only one out of two assertions is checked. This patch
adds the other as conditional.

A previous discussion about adding conditional in
bch2_dev_btree_bitmap_marked_sectors is here[2].

[1] https://syzkaller.appspot.com/bug?extid=e8eff054face85d7ea41
[2] https://lore.kernel.org/all/[email protected]/
---
 fs/bcachefs/sb-members.h | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/bcachefs/sb-members.h b/fs/bcachefs/sb-members.h
index 
762083b564ee5909071eb4235c3d5cd6e72ee519..3141791491928930a707a6a16579c6d2e11e3700
 100644
--- a/fs/bcachefs/sb-members.h
+++ b/fs/bcachefs/sb-members.h
@@ -347,12 +347,16 @@ void bch2_dev_errors_reset(struct bch_dev *);
 static inline bool bch2_dev_btree_bitmap_marked_sectors(struct bch_dev *ca, 
u64 start, unsigned sectors)
 {
        u64 end = start + sectors;
+       u8 bitmap_shift = ca->mi.btree_bitmap_shift;
 
-       if (end > 64ULL << ca->mi.btree_bitmap_shift)
+       if (bitmap_shift > 57)
+               return true;
+
+       if (end > 64ULL << bitmap_shift)
                return false;
 
-       for (unsigned bit = start >> ca->mi.btree_bitmap_shift;
-            (u64) bit << ca->mi.btree_bitmap_shift < end;
+       for (unsigned bit = start >> bitmap_shift;
+            (u64) bit << bitmap_shift < end;
             bit++)
                if (!(ca->mi.btree_allocated_bitmap & BIT_ULL(bit)))
                        return false;

---
base-commit: 42f7652d3eb527d03665b09edac47f85fb600924
change-id: 20241022-fix-missing-cond-bcachefs-a889f51e8aa2

Best regards,
-- 
Manas <[email protected]>



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