5.4-stable review patch. If anyone has any objections, please let me know.
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From: Pali Rohár pali@kernel.org
commit e2a8910af01653c1c268984855629d71fb81f404 upstream.
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) pc@manguebit.com Signed-off-by: Pali Rohár pali@kernel.org Signed-off-by: Steve French stfrench@microsoft.com [use variable name symlink_buf, the other buf->InodeType accesses are not used in current version so skip] Signed-off-by: Mahmoud Adam mngyadam@amazon.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/cifs/smb2ops.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index b2e45e168548b..64ac683498e03 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -2539,6 +2539,12 @@ parse_reparse_posix(struct reparse_posix_data *symlink_buf,
/* See MS-FSCC 2.1.2.6 for the 'NFS' style reparse tags */ len = le16_to_cpu(symlink_buf->ReparseDataLength); + if (len < sizeof(symlink_buf->InodeType)) { + cifs_dbg(VFS, "srv returned malformed nfs buffer\n"); + return -EIO; + } + + len -= sizeof(symlink_buf->InodeType);
if (le64_to_cpu(symlink_buf->InodeType) != NFS_SPECFILE_LNK) { cifs_dbg(VFS, "%lld not a supported symlink type\n",