The patch titled Subject: nilfs2: fix general protection fault in nilfs_lookup_dirty_data_buffers() has been added to the -mm mm-hotfixes-unstable branch. Its filename is nilfs2-fix-general-protection-fault-in-nilfs_lookup_dirty_data_buffers.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days

------------------------------------------------------ From: Ryusuke Konishi konishi.ryusuke@gmail.com Subject: nilfs2: fix general protection fault in nilfs_lookup_dirty_data_buffers() Date: Sat, 5 Aug 2023 22:20:38 +0900

A syzbot stress test reported that create_empty_buffers() called from nilfs_lookup_dirty_data_buffers() can cause a general protection fault.

Analysis using its reproducer revealed that the back reference "mapping" from a page/folio has been changed to NULL after dirty page/folio gang lookup in nilfs_lookup_dirty_data_buffers().

Fix this issue by excluding pages/folios from being collected if, after acquiring a lock on each page/folio, its back reference "mapping" differs from the pointer to the address space struct that held the page/folio.

Link: https://lkml.kernel.org/r/20230805132038.6435-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi konishi.ryusuke@gmail.com Reported-by: syzbot+0ad741797f4565e7e2d2@syzkaller.appspotmail.com Closes: https://lkml.kernel.org/r/0000000000002930a705fc32b231@google.com Tested-by: Ryusuke Konishi konishi.ryusuke@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/nilfs2/segment.c | 5 +++++ 1 file changed, 5 insertions(+)

--- a/fs/nilfs2/segment.c~nilfs2-fix-general-protection-fault-in-nilfs_lookup_dirty_data_buffers +++ a/fs/nilfs2/segment.c @@ -725,6 +725,11 @@ static size_t nilfs_lookup_dirty_data_bu struct folio *folio = fbatch.folios[i];

folio_lock(folio); + if (unlikely(folio->mapping != mapping)) { + /* Exclude folios removed from the address space */ + folio_unlock(folio); + continue; + } head = folio_buffers(folio); if (!head) { create_empty_buffers(&folio->page, i_blocksize(inode), 0); _

Patches currently in -mm which might be from konishi.ryusuke@gmail.com are

nilfs2-fix-general-protection-fault-in-nilfs_lookup_dirty_data_buffers.patch