From 2f012f2baca140c488e43d27a374029c1e59098d Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Sat, 13 May 2023 19:24:28 +0900 Subject: [PATCH] nilfs2: fix incomplete buffer cleanup in nilfs_btnode_abort_change_key() A syzbot fault injection test reported that nilfs_btnode_create_block, a helper function that allocates a new node block for b-trees, causes a kernel BUG for disk images where the file system block size is smaller than the page size. This was due to unexpected flags on the newly allocated buffer head, and it turned out to be because the buffer flags were not cleared by nilfs_btnode_abort_change_key() after an error occurred during a b-tree update operation and the buffer was later reused in that state. Fix this issue by using nilfs_btnode_delete() to abandon the unused preallocated buffer in nilfs_btnode_abort_change_key(). Link: https://lkml.kernel.org/r/20230513102428.10223-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi Reported-by: syzbot+b0a35a5c1f7e846d3b09@syzkaller.appspotmail.com Closes: https://lkml.kernel.org/r/000000000000d1d6c205ebc4d512@google.com Tested-by: Ryusuke Konishi Cc: Signed-off-by: Andrew Morton --- fs/nilfs2/btnode.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/nilfs2/btnode.c b/fs/nilfs2/btnode.c index e956f886a1a1..5710833ac1cc 100644 --- a/fs/nilfs2/btnode.c +++ b/fs/nilfs2/btnode.c @@ -285,6 +285,14 @@ void nilfs_btnode_abort_change_key(struct address_space *btnc, if (nbh == NULL) { /* blocksize == pagesize */ xa_erase_irq(&btnc->i_pages, newkey); unlock_page(ctxt->bh->b_page); - } else - brelse(nbh); + } else { + /* + * When canceling a buffer that a prepare operation has + * allocated to copy a node block to another location, use + * nilfs_btnode_delete() to initialize and release the buffer + * so that the buffer flags will not be in an inconsistent + * state when it is reallocated. + */ + nilfs_btnode_delete(nbh); + } }