From 8ad8aa353524d89fa2e09522f3078166ff78ec42 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Thu, 6 Sep 2018 12:47:51 +0300 Subject: [PATCH] cifs: prevent integer overflow in nxt_dir_entry() The "old_entry + le32_to_cpu(pDirInfo->NextEntryOffset)" can wrap around so I have added a check for integer overflow. Reported-by: Dr Silvio Cesare of InfoSect Reviewed-by: Ronnie Sahlberg Reviewed-by: Aurelien Aptel Signed-off-by: Dan Carpenter Signed-off-by: Steve French CC: Stable --- fs/cifs/readdir.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c index eeab81c9452f..e169e1a5fd35 100644 --- a/fs/cifs/readdir.c +++ b/fs/cifs/readdir.c @@ -376,8 +376,15 @@ static char *nxt_dir_entry(char *old_entry, char *end_of_smb, int level) new_entry = old_entry + sizeof(FIND_FILE_STANDARD_INFO) + pfData->FileNameLength; - } else - new_entry = old_entry + le32_to_cpu(pDirInfo->NextEntryOffset); + } else { + u32 next_offset = le32_to_cpu(pDirInfo->NextEntryOffset); + + if (old_entry + next_offset < old_entry) { + cifs_dbg(VFS, "invalid offset %u\n", next_offset); + return NULL; + } + new_entry = old_entry + next_offset; + } cifs_dbg(FYI, "new entry %p old entry %p\n", new_entry, old_entry); /* validate that new_entry is not past end of SMB */ if (new_entry >= end_of_smb) {