* [PATCH] cifs: fix parsing of symbolic link error response
@ 2019-07-09 8:41 Ronnie Sahlberg
0 siblings, 0 replies; only message in thread
From: Ronnie Sahlberg @ 2019-07-09 8:41 UTC (permalink / raw)
To: linux-cifs; +Cc: Steve French, Ronnie Sahlberg
RHBZ: 1672539
In smb2_query_symlink(), if we are parsing the error buffer but it is not something
we recognize as a symlink we should return -EINVAL and not -ENOENT.
I.e. the entry does exist, it is just not something we recognize.
Additionally, add check to verify that that the errortag and the reparsetag all make sense.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
---
fs/cifs/smb2ops.c | 14 ++++++++++----
fs/cifs/smb2pdu.h | 2 ++
2 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 4b0b14946343..e704e04891fb 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -2605,26 +2605,32 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
err_buf = err_iov.iov_base;
if (le32_to_cpu(err_buf->ByteCount) < sizeof(struct smb2_symlink_err_rsp) ||
err_iov.iov_len < SMB2_SYMLINK_STRUCT_SIZE) {
- rc = -ENOENT;
+ rc = -EINVAL;
+ goto querty_exit;
+ }
+
+ symlink = (struct smb2_symlink_err_rsp *)err_buf->ErrorData;
+ if (le32_to_cpu(symlink->SymLinkErrorTag) != SYMLINK_ERROR_TAG ||
+ le32_to_cpu(symlink->ReparseTag) != IO_REPARSE_TAG_SYMLINK) {
+ rc = -EINVAL;
goto querty_exit;
}
/* open must fail on symlink - reset rc */
rc = 0;
- symlink = (struct smb2_symlink_err_rsp *)err_buf->ErrorData;
sub_len = le16_to_cpu(symlink->SubstituteNameLength);
sub_offset = le16_to_cpu(symlink->SubstituteNameOffset);
print_len = le16_to_cpu(symlink->PrintNameLength);
print_offset = le16_to_cpu(symlink->PrintNameOffset);
if (err_iov.iov_len < SMB2_SYMLINK_STRUCT_SIZE + sub_offset + sub_len) {
- rc = -ENOENT;
+ rc = -EINVAL;
goto querty_exit;
}
if (err_iov.iov_len <
SMB2_SYMLINK_STRUCT_SIZE + print_offset + print_len) {
- rc = -ENOENT;
+ rc = -EINVAL;
goto querty_exit;
}
diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h
index 458bad01ca74..7e2e782f8edd 100644
--- a/fs/cifs/smb2pdu.h
+++ b/fs/cifs/smb2pdu.h
@@ -166,6 +166,8 @@ struct smb2_err_rsp {
__u8 ErrorData[1]; /* variable length */
} __packed;
+#define SYMLINK_ERROR_TAG 0x4c4d5953
+
struct smb2_symlink_err_rsp {
__le32 SymLinkLength;
__le32 SymLinkErrorTag;
--
2.13.6
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