From 803b3a39cb096d8718c0aebc03fd19f11c7dc919 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Pali=20Roh=C3=A1r?= Date: Sun, 29 Sep 2024 12:22:40 +0200 Subject: [PATCH] cifs: Fix buffer overflow when parsing NFS reparse points MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit [ Upstream commit e2a8910af01653c1c268984855629d71fb81f404 ] ReparseDataLength is sum of the InodeType size and DataBuffer size. So to get DataBuffer size it is needed to subtract InodeType's size from ReparseDataLength. Function cifs_strndup_from_utf16() is currentlly accessing buf->DataBuffer at position after the end of the buffer because it does not subtract InodeType size from the length. Fix this problem and correctly subtract variable len. Member InodeType is present only when reparse buffer is large enough. Check for ReparseDataLength before accessing InodeType to prevent another invalid memory access. Major and minor rdev values are present also only when reparse buffer is large enough. Check for reparse buffer size before calling reparse_mkdev(). Fixes: d5ecebc4900d ("smb3: Allow query of symlinks stored as reparse points") Reviewed-by: Paulo Alcantara (Red Hat) Signed-off-by: Pali Rohár Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/smb/client/reparse.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c index 48c27581ec511..cfa03c166de8c 100644 --- a/fs/smb/client/reparse.c +++ b/fs/smb/client/reparse.c @@ -320,9 +320,16 @@ static int parse_reparse_posix(struct reparse_posix_data *buf, unsigned int len; u64 type; + len = le16_to_cpu(buf->ReparseDataLength); + if (len < sizeof(buf->InodeType)) { + cifs_dbg(VFS, "srv returned malformed nfs buffer\n"); + return -EIO; + } + + len -= sizeof(buf->InodeType); + switch ((type = le64_to_cpu(buf->InodeType))) { case NFS_SPECFILE_LNK: - len = le16_to_cpu(buf->ReparseDataLength); data->symlink_target = cifs_strndup_from_utf16(buf->DataBuffer, len, true, cifs_sb->local_nls); @@ -482,12 +489,18 @@ bool cifs_reparse_point_to_fattr(struct cifs_sb_info *cifs_sb, u32 tag = data->reparse.tag; if (tag == IO_REPARSE_TAG_NFS && buf) { + if (le16_to_cpu(buf->ReparseDataLength) < sizeof(buf->InodeType)) + return false; switch (le64_to_cpu(buf->InodeType)) { case NFS_SPECFILE_CHR: + if (le16_to_cpu(buf->ReparseDataLength) != sizeof(buf->InodeType) + 8) + return false; fattr->cf_mode |= S_IFCHR; fattr->cf_rdev = reparse_nfs_mkdev(buf); break; case NFS_SPECFILE_BLK: + if (le16_to_cpu(buf->ReparseDataLength) != sizeof(buf->InodeType) + 8) + return false; fattr->cf_mode |= S_IFBLK; fattr->cf_rdev = reparse_nfs_mkdev(buf); break; -- 2.47.2