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| author | Pali Rohár <pali@kernel.org> | 2024-09-28 23:59:47 +0200 |
|---|---|---|
| committer | Steve French <stfrench@microsoft.com> | 2024-10-03 19:06:13 +0200 |
| commit | 556ac52bb1e76cc28fd30aa117b42989965b3efd (patch) | |
| tree | 6938e136aa7ea34a67e117e46388d5cb751535c4 | |
| parent | cifs: Fix buffer overflow when parsing NFS reparse points (diff) | |
| download | linux-556ac52bb1e76cc28fd30aa117b42989965b3efd.tar.xz linux-556ac52bb1e76cc28fd30aa117b42989965b3efd.zip | |
cifs: Validate content of NFS reparse point buffer
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@kernel.org>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
| -rw-r--r-- | fs/smb/client/reparse.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c index 8ea7a848aa39..f0cfcf32de19 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); @@ -341,8 +353,19 @@ 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", |