From: Ryusuke Konishi konishi.ryusuke@gmail.com
stable inclusion from stable-v4.19.292 commit a3c3b4cbf9b8554120fb230e6516e980c6277487 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IARYB6 CVE: CVE-2024-46781
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit f8654743a0e6909dc634cbfad6db6816f10f3399 upstream.
During unmount process of nilfs2, nothing holds nilfs_root structure after nilfs2 detaches its writer in nilfs_detach_log_writer(). Previously, nilfs_evict_inode() could cause use-after-free read for nilfs_root if inodes are left in "garbage_list" and released by nilfs_dispose_list at the end of nilfs_detach_log_writer(), and this bug was fixed by commit 9b5a04ac3ad9 ("nilfs2: fix use-after-free bug of nilfs_root in nilfs_evict_inode()").
However, it turned out that there is another possibility of UAF in the call path where mark_inode_dirty_sync() is called from iput():
nilfs_detach_log_writer() nilfs_dispose_list() iput() mark_inode_dirty_sync() __mark_inode_dirty() nilfs_dirty_inode() __nilfs_mark_inode_dirty() nilfs_load_inode_block() --> causes UAF of nilfs_root struct
This can happen after commit 0ae45f63d4ef ("vfs: add support for a lazytime mount option"), which changed iput() to call mark_inode_dirty_sync() on its final reference if i_state has I_DIRTY_TIME flag and i_nlink is non-zero.
This issue appears after commit 28a65b49eb53 ("nilfs2: do not write dirty data after degenerating to read-only") when using the syzbot reproducer, but the issue has potentially existed before.
Fix this issue by adding a "purging flag" to the nilfs structure, setting that flag while disposing the "garbage_list" and checking it in __nilfs_mark_inode_dirty().
Unlike commit 9b5a04ac3ad9 ("nilfs2: fix use-after-free bug of nilfs_root in nilfs_evict_inode()"), this patch does not rely on ns_writer to determine whether to skip operations, so as not to break recovery on mount. The nilfs_salvage_orphan_logs routine dirties the buffer of salvaged data before attaching the log writer, so changing __nilfs_mark_inode_dirty() to skip the operation when ns_writer is NULL will cause recovery write to fail. The purpose of using the cleanup-only flag is to allow for narrowing of such conditions.
Link: https://lkml.kernel.org/r/20230728191318.33047-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi konishi.ryusuke@gmail.com Reported-by: syzbot+74db8b3087f293d3a13a@syzkaller.appspotmail.com Closes: https://lkml.kernel.org/r/000000000000b4e906060113fd63@google.com Fixes: 0ae45f63d4ef ("vfs: add support for a lazytime mount option") Tested-by: Ryusuke Konishi konishi.ryusuke@gmail.com Cc: stable@vger.kernel.org # 4.0+ Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zeng Heng zengheng4@huawei.com --- fs/nilfs2/inode.c | 8 ++++++++ fs/nilfs2/segment.c | 2 ++ fs/nilfs2/the_nilfs.h | 2 ++ 3 files changed, 12 insertions(+)
diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c index cbfe6ed764d3..d720a26da92e 100644 --- a/fs/nilfs2/inode.c +++ b/fs/nilfs2/inode.c @@ -963,9 +963,17 @@ int nilfs_set_file_dirty(struct inode *inode, unsigned int nr_dirty)
int __nilfs_mark_inode_dirty(struct inode *inode, int flags) { + struct the_nilfs *nilfs = inode->i_sb->s_fs_info; struct buffer_head *ibh; int err;
+ /* + * Do not dirty inodes after the log writer has been detached + * and its nilfs_root struct has been freed. + */ + if (unlikely(nilfs_purging(nilfs))) + return 0; + err = nilfs_load_inode_block(inode, &ibh); if (unlikely(err)) { nilfs_msg(inode->i_sb, KERN_WARNING, diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c index 04cd0a643234..633809581852 100644 --- a/fs/nilfs2/segment.c +++ b/fs/nilfs2/segment.c @@ -2853,6 +2853,7 @@ void nilfs_detach_log_writer(struct super_block *sb) nilfs_segctor_destroy(nilfs->ns_writer); nilfs->ns_writer = NULL; } + set_nilfs_purging(nilfs);
/* Force to free the list of dirty files */ spin_lock(&nilfs->ns_inode_lock); @@ -2865,4 +2866,5 @@ void nilfs_detach_log_writer(struct super_block *sb) up_write(&nilfs->ns_segctor_sem);
nilfs_dispose_list(nilfs, &garbage_list, 1); + clear_nilfs_purging(nilfs); } diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h index dba7e3fe53dd..95a779196acb 100644 --- a/fs/nilfs2/the_nilfs.h +++ b/fs/nilfs2/the_nilfs.h @@ -29,6 +29,7 @@ enum { THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */ THE_NILFS_GC_RUNNING, /* gc process is running */ THE_NILFS_SB_DIRTY, /* super block is dirty */ + THE_NILFS_PURGING, /* disposing dirty files for cleanup */ };
/** @@ -208,6 +209,7 @@ THE_NILFS_FNS(INIT, init) THE_NILFS_FNS(DISCONTINUED, discontinued) THE_NILFS_FNS(GC_RUNNING, gc_running) THE_NILFS_FNS(SB_DIRTY, sb_dirty) +THE_NILFS_FNS(PURGING, purging)
/* * Mount option operations