6.10-stable review patch. If anyone has any objections, please let me know.
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From: Steve French stfrench@microsoft.com
commit e4be320eeca842a3d7648258ee3673f1755a5a59 upstream.
Mandatory locking is enforced for cached reads, which violates default posix semantics, and also it is enforced inconsistently. This affected recent versions of libreoffice, and can be demonstrated by opening a file twice from the same client, locking it from handle one and trying to read from it from handle two (which fails, returning EACCES).
There is already a mount option "forcemandatorylock" (which defaults to off), so with this change only when the user intentionally specifies "forcemandatorylock" on mount will we break posix semantics on read to a locked range (ie we will only fail in this case, if the user mounts with "forcemandatorylock").
An earlier patch fixed the write path.
Fixes: 85160e03a79e ("CIFS: Implement caching mechanism for mandatory brlocks") Cc: stable@vger.kernel.org Cc: Pavel Shilovsky piastryyy@gmail.com Reviewed-by: David Howells dhowells@redhat.com Reported-by: abartlet@samba.org Reported-by: Kevin Ottens kevin.ottens@enioka.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/client/file.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
--- a/fs/smb/client/file.c +++ b/fs/smb/client/file.c @@ -2912,9 +2912,7 @@ cifs_strict_readv(struct kiocb *iocb, st if (!CIFS_CACHE_READ(cinode)) return netfs_unbuffered_read_iter(iocb, to);
- if (cap_unix(tcon->ses) && - (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) && - ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0)) { + if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0) { if (iocb->ki_flags & IOCB_DIRECT) return netfs_unbuffered_read_iter(iocb, to); return netfs_buffered_read_iter(iocb, to);