2.6.28-stable review patch. If anyone has any objections, please let us know. ------------------ From: Steve French commit c6fbba0546d3ead18d4a623e76e28bcbaa66a325 upstream. The paths in a DFS request are supposed to only have a single preceding backslash, but we are sending them with a double backslash. This is exposing a bug in Windows where it also sends a path in the response that has a double backslash. The existing code that builds the mount option string however expects a double backslash prefix in a couple of places when it tries to use the path returned by build_path_from_dentry. Fix compose_mount_options to expect properly formed DFS paths (single backslash at front). Also clean up error handling in that function. There was a possible NULL pointer dereference and situations where a partially built option string would be returned. Tested against Samba 3.0.28-ish server and Samba 3.3 and Win2k8. Signed-off-by: Jeff Layton Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/cifs/cifs_dfs_ref.c | 48 ++++++++++++++++++++++++++++++++++++------------ 1 file changed, 36 insertions(+), 12 deletions(-) --- a/fs/cifs/cifs_dfs_ref.c +++ b/fs/cifs/cifs_dfs_ref.c @@ -122,7 +122,7 @@ static char *compose_mount_options(const char **devname) { int rc; - char *mountdata; + char *mountdata = NULL; int md_len; char *tkn_e; char *srvIP = NULL; @@ -136,10 +136,9 @@ static char *compose_mount_options(const *devname = cifs_get_share_name(ref->node_name); rc = dns_resolve_server_name_to_ip(*devname, &srvIP); if (rc != 0) { - cERROR(1, ("%s: Failed to resolve server part of %s to IP", - __func__, *devname)); - mountdata = ERR_PTR(rc); - goto compose_mount_options_out; + cERROR(1, ("%s: Failed to resolve server part of %s to IP: %d", + __func__, *devname, rc));; + goto compose_mount_options_err; } /* md_len = strlen(...) + 12 for 'sep+prefixpath=' * assuming that we have 'unc=' and 'ip=' in @@ -149,8 +148,8 @@ static char *compose_mount_options(const strlen(ref->node_name) + 12; mountdata = kzalloc(md_len+1, GFP_KERNEL); if (mountdata == NULL) { - mountdata = ERR_PTR(-ENOMEM); - goto compose_mount_options_out; + rc = -ENOMEM; + goto compose_mount_options_err; } /* copy all options except of unc,ip,prefixpath */ @@ -197,18 +196,32 @@ static char *compose_mount_options(const /* find & copy prefixpath */ tkn_e = strchr(ref->node_name + 2, '\\'); - if (tkn_e == NULL) /* invalid unc, missing share name*/ - goto compose_mount_options_out; + if (tkn_e == NULL) { + /* invalid unc, missing share name*/ + rc = -EINVAL; + goto compose_mount_options_err; + } + /* + * this function gives us a path with a double backslash prefix. We + * require a single backslash for DFS. Temporarily increment fullpath + * to put it in the proper form and decrement before freeing it. + */ fullpath = build_path_from_dentry(dentry); + if (!fullpath) { + rc = -ENOMEM; + goto compose_mount_options_err; + } + ++fullpath; tkn_e = strchr(tkn_e + 1, '\\'); - if (tkn_e || strlen(fullpath) - (ref->path_consumed)) { + if (tkn_e || (strlen(fullpath) - ref->path_consumed)) { strncat(mountdata, &sep, 1); strcat(mountdata, "prefixpath="); if (tkn_e) strcat(mountdata, tkn_e + 1); - strcat(mountdata, fullpath + (ref->path_consumed)); + strcat(mountdata, fullpath + ref->path_consumed); } + --fullpath; kfree(fullpath); /*cFYI(1,("%s: parent mountdata: %s", __func__,sb_mountdata));*/ @@ -217,6 +230,11 @@ static char *compose_mount_options(const compose_mount_options_out: kfree(srvIP); return mountdata; + +compose_mount_options_err: + kfree(mountdata); + mountdata = ERR_PTR(rc); + goto compose_mount_options_out; } @@ -309,13 +327,19 @@ cifs_dfs_follow_mountpoint(struct dentry goto out_err; } + /* + * The MSDFS spec states that paths in DFS referral requests and + * responses must be prefixed by a single '\' character instead of + * the double backslashes usually used in the UNC. This function + * gives us the latter, so we must adjust the result. + */ full_path = build_path_from_dentry(dentry); if (full_path == NULL) { rc = -ENOMEM; goto out_err; } - rc = get_dfs_path(xid, ses , full_path, cifs_sb->local_nls, + rc = get_dfs_path(xid, ses , full_path + 1, cifs_sb->local_nls, &num_referrals, &referrals, cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/