commit 67ea5bea7f84a9a58e05a4f28d787ff3322a3029
Author: Oswald Buddenhagen <o...@users.sf.net>
Date:   Mon Nov 11 17:24:38 2019 +0100

    handle bogus IMAP FETCH responses more robustly
    
    don't use assert()s when the error condition can stem not only from
    errors in mbsync's logic, but also from the IMAP stream being corrupted.
    
    amends 72be55b0e.
    
    REFMAIL: 20191021233411.55ctuvslkfqf2pna@koblih.localdomain

 src/drv_imap.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/drv_imap.c b/src/drv_imap.c
index 4d3a038..48bf6ec 100644
--- a/src/drv_imap.c
+++ b/src/drv_imap.c
@@ -974,7 +974,7 @@ parse_fetch_rsp( imap_store_t *ctx, list_t *list, char *s 
ATTR_UNUSED )
        msg_data_t *msgdata;
        imap_cmd_t *cmdp;
        uchar mask = 0, status = 0;
-       uint i, uid = 0, size = 0;
+       uint i, uid = 0, need_uid = 0, size = 0;
        time_t date = 0;
 
        if (!is_list( list )) {
@@ -990,6 +990,7 @@ parse_fetch_rsp( imap_store_t *ctx, list_t *list, char *s 
ATTR_UNUSED )
                                        error( "IMAP error: unable to parse 
UID\n" );
                                        goto ffail;
                                }
+                               continue;  // This *is* the UID.
                        } else if (!strcmp( "FLAGS", tmp->val )) {
                                tmp = tmp->next;
                                if (is_list( tmp )) {
@@ -1018,6 +1019,7 @@ parse_fetch_rsp( imap_store_t *ctx, list_t *list, char *s 
ATTR_UNUSED )
                                                }
                                        }
                                        status |= M_FLAGS;
+                                       continue;  // This may legitimately 
come without UID.
                                } else {
                                        error( "IMAP error: unable to parse 
FLAGS\n" );
                                        goto ffail;
@@ -1099,17 +1101,27 @@ parse_fetch_rsp( imap_store_t *ctx, list_t *list, char 
*s ATTR_UNUSED )
                                }
                        }
                }
+               need_uid = 1;
        }
 
        if (!uid) {
-               assert( !body && !tuid && !msgid );
+               if (need_uid) {
+                       error( "IMAP error: received payload without UID\n" );
+                       goto ffail;
+               }
                // Ignore async flag updates for now.
        } else if ((cmdp = ctx->in_progress) && cmdp->param.lastuid) {
-               assert( !body && !tuid && !msgid );
+               if (need_uid || (status & M_FLAGS)) {
+                       error( "IMAP error: received extraneous data in 
response to UID query\n" );
+                       goto ffail;
+               }
                // Workaround for server not sending UIDNEXT and/or APPENDUID.
                ctx->uidnext = uid + 1;
        } else if (body) {
-               assert( !tuid && !msgid );
+               if (tuid || msgid) {  // Only those that leak; ignore others.
+                       error( "IMAP error: received extraneous data with full 
message\n" );
+                       goto ffail;
+               }
                for (cmdp = ctx->in_progress; cmdp; cmdp = cmdp->next)
                        if (cmdp->param.uid == uid)
                                goto gotuid;


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