Downgrade DER comparison and offset lookup failures to be handled as match

failures.

diff --git a/src/softmagic.c b/src/softmagic.c
index 29533b5cec95546db1fadf6610e53465d2e47c51..464e11d53ca3601e62767914bc4dca184543bb5e 100644 (file)
--- a/src/softmagic.c
+++ b/src/softmagic.c
@@ -32,7 +32,7 @@
 #include "file.h"
 
 #ifndef        lint
-FILE_RCSID("@(#)$File: softmagic.c,v 1.229 2016/03/21 23:04:40 christos Exp $")
+FILE_RCSID("@(#)$File: softmagic.c,v 1.230 2016/04/18 15:10:34 christos Exp $")
 #endif /* lint */
 
 #include "magic.h"
@@ -186,11 +186,11 @@ match(struct magic_set *ms, struct magic *magic, uint32_t nmagic,
                     ((text && (m->str_flags & FLT) == STRING_BINTEST) ||
                      (!text && (m->str_flags & FLT) == STRING_TEXTTEST))) ||
                    (m->flag & mode) != mode) {
+flush:
                        /* Skip sub-tests */
-                       while (magindex + 1 < nmagic &&
-                               magic[magindex + 1].cont_level != 0 &&
-                              ++magindex)
-                               continue;
+                       while (magindex < nmagic - 1 &&
+                           magic[magindex + 1].cont_level != 0)
+                               magindex++;
                        continue; /* Skip to next top-level test*/
                }
 
@@ -227,10 +227,7 @@ match(struct magic_set *ms, struct magic *magic, uint32_t nmagic,
                         * main entry didn't match,
                         * flush its continuations
                         */
-                       while (magindex < nmagic - 1 &&
-                           magic[magindex + 1].cont_level != 0)
-                               magindex++;
-                       continue;
+                       goto flush;
                }
 
                if ((e = handle_annotation(ms, m)) != 0) {
@@ -255,8 +252,14 @@ match(struct magic_set *ms, struct magic *magic, uint32_t nmagic,
                if (print && mprint(ms, m) == -1)
                        return -1;
 
-               if (moffset(ms, m, nbytes, &ms->c.li[cont_level].off) == -1)
+               switch (moffset(ms, m, nbytes, &ms->c.li[cont_level].off)) {
+               case -1:
                        return -1;
+               case 0:
+                       goto flush;
+               default:
+                       break;
+               }
 
                /* and any continuations that match */
                if (file_check_mem(ms, ++cont_level) == -1)
@@ -362,9 +365,16 @@ match(struct magic_set *ms, struct magic *magic, uint32_t nmagic,
                                if (print && mprint(ms, m) == -1)
                                        return -1;
 
-                               if (moffset(ms, m, nbytes,
-                                   &ms->c.li[cont_level].off) == -1)
+                               switch (moffset(ms, m, nbytes,
+                                   &ms->c.li[cont_level].off)) {
+                               case -1:
                                        return -1;
+                               case 0:
+                                       flush = 1;
+                                       break;
+                               default:
+                                       break;
+                               }
 
                                if (*m->desc)
                                        *need_separator = 1;
@@ -813,9 +823,13 @@ moffset(struct magic_set *ms, struct magic *m, size_t nbytes, int32_t *op)
        case FILE_DER:
                {
                        o = der_offs(ms, m, nbytes);
-                       if (o == -1) {
-                               file_error(ms, 0, "EOF computing DER offset");
-                               return -1;
+                       if (o == -1 || (size_t)o > nbytes) {
+                               if ((ms->flags & MAGIC_DEBUG) != 0) {
+                                       (void)fprintf(stderr,
+                                           "Bad DER offset %d nbytes=%zu",
+                                           o, nbytes);
+                               }
+                               return 0;
                        }
                        break;
                }
@@ -825,12 +839,13 @@ moffset(struct magic_set *ms, struct magic *m, size_t nbytes, int32_t *op)
                break;
        }
 
-       if ((size_t)o >= nbytes) {
-               file_error(ms, 0, "Offset out of range");
+       if ((size_t)o > nbytes) {
+               file_error(ms, 0, "Offset out of range %zu > %zu",
+                   (size_t)o, nbytes);
                return -1;
        }
        *op = o;
-       return 0;
+       return 1;
 }
 
 private uint32_t
@@ -2107,8 +2122,13 @@ magiccheck(struct magic_set *ms, struct magic *m)
                return 1;
        case FILE_DER:
                matched = der_cmp(ms, m);
-               if (matched == -1)
-                       file_error(ms, 0, "EOF comparing DER entries");
+               if (matched == -1) {
+                       if ((ms->flags & MAGIC_DEBUG) != 0) {
+                               (void) fprintf(stderr,
+                                   "EOF comparing DER entries");
+                       }
+                       return 0;
+               }
                return matched;
        default:
                file_magerror(ms, "invalid type %d in magiccheck()", m->type);