7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dominik Maier commit a377a3645c7d0246af0bc4ef24db94bb2670bdde upstream. In id_mode_to_cifs_acl(), while the chown branch reserves sizeof(struct smb_ntsd) + 2 * sizeof(struct smb_sid) (plus sizeof(struct smb_acl) and the worst-case ACE space after commit 0ee150794c75 ("smb: client: fix heap overflow in DACL owner/group rewrite")), the chmod branch only adds 2 * sizeof(struct smb_ace) or 5 * sizeof(struct smb_ace) to secdesclen (or 1 * sizeof(struct smb_ace) on posix). However, the chmod branch also invokes build_sec_desc() -> copy_sec_desc(), which unconditionally writes the Owner SID at pnntsd + sidsoffset and the Group SID at pnntsd + sidsoffset + sizeof(struct smb_sid) (2 * 68 = 136 bytes total), and set_chmod_dacl() always writes a struct smb_acl header (8 bytes) even when the source descriptor has dacloffset == 0. When a security descriptor has compact or overlapping Owner/Group SIDs (or dacloffset == 0), calling chmod() under-allocates pnntsd and writes past the end of the slab buffer. Reserve sizeof(struct smb_acl) + 2 * sizeof(struct smb_sid) (plus sizeof(struct smb_ntsd) on the posix path) in the chmod branch of id_mode_to_cifs_acl(). Fixes: 7ee0b4c635c0 ("cifs: fix hardcoded default security descriptor length") Fixes: f5065508897a ("cifs: Retain old ACEs when converting between mode bits and ACL.") Assisted-by: ARTIST LLM Signed-off-by: Dominik Maier Cc: stable@vger.kernel.org Signed-off-by: Paulo Alcantara Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/cifsacl.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/fs/smb/client/cifsacl.c +++ b/fs/smb/client/cifsacl.c @@ -1826,12 +1826,15 @@ id_mode_to_cifs_acl(struct inode *inode, /* Potentially, five new ACEs can be added to the ACL for U,G,O mapping */ if (pnmode && *pnmode != NO_CHANGE_64) { /* chmod */ + nsecdesclen = sizeof(struct smb_acl) + + 2 * sizeof(struct smb_sid); if (posix) - nsecdesclen = 1 * sizeof(struct smb_ace); + nsecdesclen += sizeof(struct smb_ntsd) + + sizeof(struct smb_ace); else if (mode_from_sid) - nsecdesclen = secdesclen + (2 * sizeof(struct smb_ace)); + nsecdesclen += secdesclen + 2 * sizeof(struct smb_ace); else /* cifsacl */ - nsecdesclen = secdesclen + (5 * sizeof(struct smb_ace)); + nsecdesclen += secdesclen + 5 * sizeof(struct smb_ace); } else { /* chown */ /* When ownership changes, changes new owner sid length could be different */ nsecdesclen = sizeof(struct smb_ntsd) + (sizeof(struct smb_sid) * 2);