5.4-stable review patch. If anyone has any objections, please let me know.
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From: Ryusuke Konishi konishi.ryusuke@gmail.com
commit 4811f7af6090e8f5a398fbdd766f903ef6c0d787 upstream.
Syzbot reported that a buffer state inconsistency was detected in nilfs_btnode_create_block(), triggering a kernel bug.
It is not appropriate to treat this inconsistency as a bug; it can occur if the argument block address (the buffer index of the newly created block) is a virtual block number and has been reallocated due to corruption of the bitmap used to manage its allocation state.
So, modify nilfs_btnode_create_block() and its callers to treat it as a possible filesystem error, rather than triggering a kernel bug.
Link: https://lkml.kernel.org/r/20240725052007.4562-1-konishi.ryusuke@gmail.com Fixes: a60be987d45d ("nilfs2: B-tree node cache") Signed-off-by: Ryusuke Konishi konishi.ryusuke@gmail.com Reported-by: syzbot+89cc4f2324ed37988b60@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=89cc4f2324ed37988b60 Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/nilfs2/btnode.c | 25 ++++++++++++++++++++----- fs/nilfs2/btree.c | 4 ++-- 2 files changed, 22 insertions(+), 7 deletions(-)
--- a/fs/nilfs2/btnode.c +++ b/fs/nilfs2/btnode.c @@ -51,12 +51,21 @@ nilfs_btnode_create_block(struct address
bh = nilfs_grab_buffer(inode, btnc, blocknr, BIT(BH_NILFS_Node)); if (unlikely(!bh)) - return NULL; + return ERR_PTR(-ENOMEM);
if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) || buffer_dirty(bh))) { - brelse(bh); - BUG(); + /* + * The block buffer at the specified new address was already + * in use. This can happen if it is a virtual block number + * and has been reallocated due to corruption of the bitmap + * used to manage its allocation state (if not, the buffer + * clearing of an abandoned b-tree node is missing somewhere). + */ + nilfs_error(inode->i_sb, + "state inconsistency probably due to duplicate use of b-tree node block address %llu (ino=%lu)", + (unsigned long long)blocknr, inode->i_ino); + goto failed; } memset(bh->b_data, 0, i_blocksize(inode)); bh->b_bdev = inode->i_sb->s_bdev; @@ -67,6 +76,12 @@ nilfs_btnode_create_block(struct address unlock_page(bh->b_page); put_page(bh->b_page); return bh; + +failed: + unlock_page(bh->b_page); + put_page(bh->b_page); + brelse(bh); + return ERR_PTR(-EIO); }
int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr, @@ -217,8 +232,8 @@ retry: }
nbh = nilfs_btnode_create_block(btnc, newkey); - if (!nbh) - return -ENOMEM; + if (IS_ERR(nbh)) + return PTR_ERR(nbh);
BUG_ON(nbh == obh); ctxt->newbh = nbh; --- a/fs/nilfs2/btree.c +++ b/fs/nilfs2/btree.c @@ -63,8 +63,8 @@ static int nilfs_btree_get_new_block(con struct buffer_head *bh;
bh = nilfs_btnode_create_block(btnc, ptr); - if (!bh) - return -ENOMEM; + if (IS_ERR(bh)) + return PTR_ERR(bh);
set_buffer_nilfs_volatile(bh); *bhp = bh;