From 5c2503a8e339fbc82f49d5706c5a4ad650dd9711 Mon Sep 17 00:00:00 2001 From: Igor Mammedov Date: Tue, 21 Apr 2009 19:31:05 +0400 Subject: [PATCH 1/1] Added loop check when mounting DFS tree. Added loop check when mounting DFS tree. mount will fail with ELOOP if referral walks exceed MAX_NESTED_LINK count. Signed-off-by: Igor Mammedov Acked-by: Jeff Layton Signed-off-by: Steve French --- fs/cifs/connect.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 579a628..7e5d4fd 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include #include @@ -2278,6 +2279,7 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, #ifdef CONFIG_CIFS_DFS_UPCALL struct dfs_info3_param *referrals = NULL; unsigned int num_referrals = 0; + int referral_walks_count = 0; try_mount_again: #endif full_path = NULL; @@ -2525,6 +2527,16 @@ remote_path_check: /* get referral if needed */ if (rc == -EREMOTE) { #ifdef CONFIG_CIFS_DFS_UPCALL + if (referral_walks_count > MAX_NESTED_LINKS) { + /* + * BB: when we implement proper loop detection, + * we will remove this check. But now we need it + * to prevent an indefinite loop if 'DFS tree' is + * misconfigured (i.e. has loops). + */ + rc = -ELOOP; + goto mount_fail_check; + } /* convert forward to back slashes in prepath here if needed */ if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) == 0) convert_delimiter(cifs_sb->prepath, @@ -2558,6 +2570,7 @@ remote_path_check: cleanup_volume_info(&volume_info); FreeXid(xid); kfree(full_path); + referral_walks_count++; goto try_mount_again; } #else /* No DFS support, return error on mount */ -- 1.8.2.3