From 7d1cfc10d42bbffa224ee7734f129834ad94abc8 Mon Sep 17 00:00:00 2001 From: Ronnie Sahlberg Date: Thu, 13 Dec 2018 08:06:16 +1000 Subject: cifs: check ntwrk_buf_start for NULL before dereferencing it [ Upstream commit 59a63e479ce36a3f24444c3a36efe82b78e4a8e0 ] RHBZ: 1021460 There is an issue where when multiple threads open/close the same directory ntwrk_buf_start might end up being NULL, causing the call to smbCalcSize later to oops with a NULL deref. The real bug is why this happens and why this can become NULL for an open cfile, which should not be allowed. This patch tries to avoid a oops until the time when we fix the underlying issue. Signed-off-by: Ronnie Sahlberg Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/cifs/readdir.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'fs/cifs/readdir.c') diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c index 57b039ebfb1f..43fa471c88d7 100644 --- a/fs/cifs/readdir.c +++ b/fs/cifs/readdir.c @@ -652,7 +652,14 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos, /* scan and find it */ int i; char *cur_ent; - char *end_of_smb = cfile->srch_inf.ntwrk_buf_start + + char *end_of_smb; + + if (cfile->srch_inf.ntwrk_buf_start == NULL) { + cifs_dbg(VFS, "ntwrk_buf_start is NULL during readdir\n"); + return -EIO; + } + + end_of_smb = cfile->srch_inf.ntwrk_buf_start + server->ops->calc_smb_size( cfile->srch_inf.ntwrk_buf_start); -- cgit v1.2.3