commit b3a033e3ecd3471248d474ef263aadc0059e516a upstream.
Syzbot reported that page_symlink(), called by nilfs_symlink(), triggers
memory reclamation involving the filesystem layer, which can result in
circular lock dependencies among the reader/writer semaphore
nilfs->ns_segctor_sem, s_writers percpu_rwsem (intwrite) and the
fs_reclaim pseudo lock.
This is because after commit 21fc61c73c39 ("don't put symlink bodies in
pagecache into highmem"), the gfp flags of the page cache for symbolic
links are overwritten to GFP_KERNEL via inode_nohighmem().
This is not a problem for symlinks read from the backing device, because
the __GFP_FS flag is dropped after inode_nohighmem() is called. However,
when a new symlink is created with nilfs_symlink(), the gfp flags remain
overwritten to GFP_KERNEL. Then, memory allocation called from
page_symlink() etc. triggers memory reclamation including the FS layer,
which may call nilfs_evict_inode() or nilfs_dirty_inode(). And these can
cause a deadlock if they are called while nilfs->ns_segctor_sem is held:
Fix this issue by dropping the __GFP_FS flag from the page cache GFP flags
of newly created symlinks in the same way that nilfs_new_inode() and
__nilfs_read_inode() do, as a workaround until we adopt nofs allocation
scope consistently or improve the locking constraints.
Link: https://lkml.kernel.org/r/20241020050003.4308-1-konishi.ryusuke@gmail.com
Fixes: 21fc61c73c39 ("don't put symlink bodies in pagecache into highmem")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+9ef37ac20608f4836256@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9ef37ac20608f4836256
Tested-by: syzbot+9ef37ac20608f4836256@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 08cfa12adf888db98879dbd735bc741360a34168 upstream.
Syzbot reported that a task hang occurs in vcs_open() during a fuzzing
test for nilfs2.
The root cause of this problem is that in nilfs_find_entry(), which
searches for directory entries, ignores errors when loading a directory
page/folio via nilfs_get_folio() fails.
If the filesystem images is corrupted, and the i_size of the directory
inode is large, and the directory page/folio is successfully read but
fails the sanity check, for example when it is zero-filled,
nilfs_check_folio() may continue to spit out error messages in bursts.
Fix this issue by propagating the error to the callers when loading a
page/folio fails in nilfs_find_entry().
The current interface of nilfs_find_entry() and its callers is outdated
and cannot propagate error codes such as -EIO and -ENOMEM returned via
nilfs_find_entry(), so fix it together.
Link: https://lkml.kernel.org/r/20241004033640.6841-1-konishi.ryusuke@gmail.com
Fixes: 2ba466d74ed7 ("nilfs2: directory entry operations")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: Lizhi Xu <lizhi.xu@windriver.com>
Closes: https://lkml.kernel.org/r/20240927013806.3577931-1-lizhi.xu@windriver.com
Reported-by: syzbot+8a192e8d090fa9a31135@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8a192e8d090fa9a31135
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
