4.19-stable review patch. If anyone has any objections, please let me know.
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From: Ryusuke Konishi konishi.ryusuke@gmail.com
[ Upstream commit 7373a51e7998b508af7136530f3a997b286ce81c ]
The error handling in nilfs_empty_dir() when a directory folio/page read fails is incorrect, as in the old ext2 implementation, and if the folio/page cannot be read or nilfs_check_folio() fails, it will falsely determine the directory as empty and corrupt the file system.
In addition, since nilfs_empty_dir() does not immediately return on a failed folio/page read, but continues to loop, this can cause a long loop with I/O if i_size of the directory's inode is also corrupted, causing the log writer thread to wait and hang, as reported by syzbot.
Fix these issues by making nilfs_empty_dir() immediately return a false value (0) if it fails to get a directory folio/page.
Link: https://lkml.kernel.org/r/20240604134255.7165-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi konishi.ryusuke@gmail.com Reported-by: syzbot+c8166c541d3971bf6c87@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c8166c541d3971bf6c87 Fixes: 2ba466d74ed7 ("nilfs2: directory entry operations") Tested-by: Ryusuke Konishi konishi.ryusuke@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nilfs2/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/nilfs2/dir.c b/fs/nilfs2/dir.c index 22f1f75a90c1a..552234ef22fe7 100644 --- a/fs/nilfs2/dir.c +++ b/fs/nilfs2/dir.c @@ -627,7 +627,7 @@ int nilfs_empty_dir(struct inode *inode)
kaddr = nilfs_get_page(inode, i, &page); if (IS_ERR(kaddr)) - continue; + return 0;
de = (struct nilfs_dir_entry *)kaddr; kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);