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Message-ID: <20241012112619.1762860-15-sashal@kernel.org>
Date: Sat, 12 Oct 2024 07:26:11 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Cc: Pali Rohár <pali@...nel.org>,
Paulo Alcantara <pc@...guebit.com>,
Steve French <stfrench@...rosoft.com>,
Sasha Levin <sashal@...nel.org>,
sfrench@...ba.org,
linux-cifs@...r.kernel.org,
samba-technical@...ts.samba.org
Subject: [PATCH AUTOSEL 6.11 15/16] cifs: Validate content of NFS reparse point buffer
From: Pali Rohár <pali@...nel.org>
[ Upstream commit 556ac52bb1e76cc28fd30aa117b42989965b3efd ]
Symlink target location stored in DataBuffer is encoded in UTF-16. So check
that symlink DataBuffer length is non-zero and even number. And check that
DataBuffer does not contain UTF-16 null codepoint because Linux cannot
process symlink with null byte.
DataBuffer for char and block devices is 8 bytes long as it contains two
32-bit numbers (major and minor). Add check for this.
DataBuffer buffer for sockets and fifos zero-length. Add checks for this.
Signed-off-by: Pali Rohár <pali@...nel.org>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@...guebit.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
fs/smb/client/reparse.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
index ad0e0de9a165d..7429b96a6ae5e 100644
--- a/fs/smb/client/reparse.c
+++ b/fs/smb/client/reparse.c
@@ -330,6 +330,18 @@ static int parse_reparse_posix(struct reparse_posix_data *buf,
switch ((type = le64_to_cpu(buf->InodeType))) {
case NFS_SPECFILE_LNK:
+ if (len == 0 || (len % 2)) {
+ cifs_dbg(VFS, "srv returned malformed nfs symlink buffer\n");
+ return -EIO;
+ }
+ /*
+ * Check that buffer does not contain UTF-16 null codepoint
+ * because Linux cannot process symlink with null byte.
+ */
+ if (UniStrnlen((wchar_t *)buf->DataBuffer, len/2) != len/2) {
+ cifs_dbg(VFS, "srv returned null byte in nfs symlink target location\n");
+ return -EIO;
+ }
data->symlink_target = cifs_strndup_from_utf16(buf->DataBuffer,
len, true,
cifs_sb->local_nls);
@@ -340,8 +352,19 @@ static int parse_reparse_posix(struct reparse_posix_data *buf,
break;
case NFS_SPECFILE_CHR:
case NFS_SPECFILE_BLK:
+ /* DataBuffer for block and char devices contains two 32-bit numbers */
+ if (len != 8) {
+ cifs_dbg(VFS, "srv returned malformed nfs buffer for type: 0x%llx\n", type);
+ return -EIO;
+ }
+ break;
case NFS_SPECFILE_FIFO:
case NFS_SPECFILE_SOCK:
+ /* DataBuffer for fifos and sockets is empty */
+ if (len != 0) {
+ cifs_dbg(VFS, "srv returned malformed nfs buffer for type: 0x%llx\n", type);
+ return -EIO;
+ }
break;
default:
cifs_dbg(VFS, "%s: unhandled inode type: 0x%llx\n",
--
2.43.0
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