journal: implement basic journal file verification logic

6 files changed, 471 insertions, 23 deletions

diff --git a/Makefile.am b/Makefile.am
index c90867c8da..f220b59c9c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -2384,6 +2384,14 @@ test_journal_stream_LDADD = \
 	libsystemd-journal-internal.la \
 	libsystemd-id128-internal.la
 
+test_journal_verify_SOURCES = \
+	src/journal/test-journal-verify.c
+
+test_journal_verify_LDADD = \
+	libsystemd-shared.la \
+	libsystemd-journal-internal.la \
+	libsystemd-id128-internal.la
+
 libsystemd_journal_la_SOURCES = \
 	src/journal/sd-journal.c \
 	src/systemd/sd-journal.h \
@@ -2482,12 +2490,14 @@ noinst_PROGRAMS += \
 	test-journal \
 	test-journal-send \
 	test-journal-match \
-	test-journal-stream
+	test-journal-stream \
+	test-journal-verify
 
 TESTS += \
 	test-journal \
 	test-journal-match \
-	test-journal-stream
+	test-journal-stream \
+	test-journal-verify
 
 pkginclude_HEADERS += \
 	src/systemd/sd-journal.h \
diff --git a/src/journal/journal-def.h b/src/journal/journal-def.h
index 82210bfc46..a77f69edcb 100644
--- a/src/journal/journal-def.h
+++ b/src/journal/journal-def.h
@@ -174,8 +174,8 @@ _packed_ struct Header {
         le64_t tail_object_offset;
         le64_t n_objects;
         le64_t n_entries;
-        le64_t tail_seqnum;
-        le64_t head_seqnum;
+        le64_t tail_entry_seqnum;
+        le64_t head_entry_seqnum;
         le64_t entry_array_offset;
         le64_t head_entry_realtime;
         le64_t tail_entry_realtime;
diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index 1f5e04d791..709e15eceb 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -136,7 +136,7 @@ static int journal_file_init_header(JournalFile *f, JournalFile *template) {
 
         if (template) {
                 h.seqnum_id = template->header->seqnum_id;
-                h.tail_seqnum = template->header->tail_seqnum;
+                h.tail_entry_seqnum = template->header->tail_entry_seqnum;
         } else
                 h.seqnum_id = h.file_id;
 
@@ -210,6 +210,10 @@ static int journal_file_verify_header(JournalFile *f) {
         if (le64toh(f->header->header_size) < HEADER_SIZE_MIN)
                 return -EBADMSG;
 
+        if ((le32toh(f->header->compatible_flags) & HEADER_COMPATIBLE_AUTHENTICATED) &&
+                !JOURNAL_HEADER_CONTAINS(f->header, n_tags))
+                return -EBADMSG;
+
         if ((uint64_t) f->last_stat.st_size < (le64toh(f->header->header_size) + le64toh(f->header->arena_size)))
                 return -ENODATA;
 
@@ -407,7 +411,7 @@ static uint64_t journal_file_entry_seqnum(JournalFile *f, uint64_t *seqnum) {
 
         assert(f);
 
-        r = le64toh(f->header->tail_seqnum) + 1;
+        r = le64toh(f->header->tail_entry_seqnum) + 1;
 
         if (seqnum) {
                 /* If an external seqnum counter was passed, we update
@@ -420,10 +424,10 @@ static uint64_t journal_file_entry_seqnum(JournalFile *f, uint64_t *seqnum) {
                 *seqnum = r;
         }
 
-        f->header->tail_seqnum = htole64(r);
+        f->header->tail_entry_seqnum = htole64(r);
 
-        if (f->header->head_seqnum == 0)
-                f->header->head_seqnum = htole64(r);
+        if (f->header->head_entry_seqnum == 0)
+                f->header->head_entry_seqnum = htole64(r);
 
         return r;
 }
@@ -2066,7 +2070,7 @@ static int journal_file_hmac_put_header(JournalFile *f) {
         gcry_md_write(f->hmac, &f->header->file_id, offsetof(Header, boot_id) - offsetof(Header, file_id));
         gcry_md_write(f->hmac, &f->header->seqnum_id, offsetof(Header, arena_size) - offsetof(Header, seqnum_id));
         gcry_md_write(f->hmac, &f->header->data_hash_table_offset, offsetof(Header, tail_object_offset) - offsetof(Header, data_hash_table_offset));
-        gcry_md_write(f->hmac, &f->header->head_seqnum, offsetof(Header, head_entry_realtime) - offsetof(Header, head_seqnum));
+        gcry_md_write(f->hmac, &f->header->head_entry_seqnum, offsetof(Header, head_entry_realtime) - offsetof(Header, head_entry_seqnum));
 
         return 0;
 }
@@ -2223,6 +2227,405 @@ static int journal_file_append_first_tag(JournalFile *f) {
         return 0;
 }
 
+static int journal_file_object_verify(JournalFile *f, Object *o) {
+        assert(f);
+        assert(o);
+
+        /* This does various superficial tests about the length an
+         * possible field values. It does not follow any references to
+         * other objects. */
+
+        switch (o->object.type) {
+        case OBJECT_DATA:
+                if (le64toh(o->data.entry_offset) <= 0 ||
+                    le64toh(o->data.n_entries) <= 0)
+                        return -EBADMSG;
+
+                if (le64toh(o->object.size) - offsetof(DataObject, payload) <= 0)
+                        return -EBADMSG;
+                break;
+
+        case OBJECT_FIELD:
+                if (le64toh(o->object.size) - offsetof(FieldObject, payload) <= 0)
+                        return -EBADMSG;
+                break;
+
+        case OBJECT_ENTRY:
+                if ((le64toh(o->object.size) - offsetof(EntryObject, items)) % sizeof(EntryItem) != 0)
+                        return -EBADMSG;
+
+                if ((le64toh(o->object.size) - offsetof(EntryObject, items)) / sizeof(EntryItem) <= 0)
+                        return -EBADMSG;
+
+                if (le64toh(o->entry.seqnum) <= 0 ||
+                    le64toh(o->entry.realtime) <= 0)
+                        return -EBADMSG;
+
+                break;
+
+        case OBJECT_DATA_HASH_TABLE:
+        case OBJECT_FIELD_HASH_TABLE:
+                if ((le64toh(o->object.size) - offsetof(HashTableObject, items)) % sizeof(HashItem) != 0)
+                        return -EBADMSG;
+
+                break;
+
+        case OBJECT_ENTRY_ARRAY:
+                if ((le64toh(o->object.size) - offsetof(EntryArrayObject, items)) % sizeof(le64_t) != 0)
+                        return -EBADMSG;
+
+                break;
+
+        case OBJECT_TAG:
+                if (le64toh(o->object.size) != sizeof(TagObject))
+                        return -EBADMSG;
+                break;
+        }
+
+        return 0;
+}
+
+static void draw_progress(uint64_t p, usec_t *last_usec) {
+        unsigned n, i, j, k;
+        usec_t z, x;
+
+        if (!isatty(STDOUT_FILENO))
+                return;
+
+        z = now(CLOCK_MONOTONIC);
+        x = *last_usec;
+
+        if (x != 0 && x + 40 * USEC_PER_MSEC > z)
+                return;
+
+        *last_usec = z;
+
+        n = (3 * columns()) / 4;
+        j = (n * (unsigned) p) / 65535ULL;
+        k = n - j;
+
+        fputs("\r\x1B[?25l", stdout);
+
+        for (i = 0; i < j; i++)
+                fputs("\xe2\x96\x88", stdout);
+
+        for (i = 0; i < k; i++)
+                fputs("\xe2\x96\x91", stdout);
+
+        printf(" %3lu%%", 100LU * (unsigned long) p / 65535LU);
+
+        fputs("\r\x1B[?25h", stdout);
+        fflush(stdout);
+}
+
+static void flush_progress(void) {
+        unsigned n, i;
+
+        if (!isatty(STDOUT_FILENO))
+                return;
+
+        n = (3 * columns()) / 4;
+
+        putchar('\r');
+
+        for (i = 0; i < n + 5; i++)
+                putchar(' ');
+
+        putchar('\r');
+        fflush(stdout);
+}
+
+int journal_file_verify(JournalFile *f, const char *key) {
+        int r;
+        Object *o;
+        uint64_t p = 0, q = 0, e;
+        uint64_t tag_seqnum = 0, entry_seqnum = 0, entry_monotonic = 0, entry_realtime = 0;
+        sd_id128_t entry_boot_id;
+        bool entry_seqnum_set = false, entry_monotonic_set = false, entry_realtime_set = false, found_main_entry_array = false;
+        uint64_t n_weird = 0, n_objects = 0, n_entries = 0, n_data = 0, n_fields = 0, n_data_hash_tables = 0, n_field_hash_tables = 0;
+        usec_t last_usec = 0;
+
+        assert(f);
+
+        /* First iteration: we go through all objects, verify the
+         * superficial structure, headers, hashes. */
+
+        r = journal_file_hmac_put_header(f);
+        if (r < 0) {
+                log_error("Failed to calculate HMAC of header.");
+                goto fail;
+        }
+
+        p = le64toh(f->header->header_size);
+        while (p != 0) {
+                draw_progress((65535ULL * p / le64toh(f->header->tail_object_offset)), &last_usec);
+
+                r = journal_file_move_to_object(f, -1, p, &o);
+                if (r < 0) {
+                        log_error("Invalid object at %llu", (unsigned long long) p);
+                        goto fail;
+                }
+
+                if (le64toh(f->header->tail_object_offset) < p) {
+                        log_error("Invalid tail object pointer.");
+                        r = -EBADMSG;
+                        goto fail;
+                }
+
+                n_objects ++;
+
+                r = journal_file_object_verify(f, o);
+                if (r < 0) {
+                        log_error("Invalid object contents at %llu", (unsigned long long) p);
+                        goto fail;
+                }
+
+                r = journal_file_hmac_put_object(f, -1, p);
+                if (r < 0) {
+                        log_error("Failed to calculate HMAC at %llu", (unsigned long long) p);
+                        goto fail;
+                }
+
+                if (o->object.flags & OBJECT_COMPRESSED &&
+                    !(le32toh(f->header->incompatible_flags) & HEADER_INCOMPATIBLE_COMPRESSED)) {
+                        log_error("Compressed object without compression at %llu", (unsigned long long) p);
+                        r = -EBADMSG;
+                        goto fail;
+                }
+
+                if (o->object.flags & OBJECT_COMPRESSED &&
+                    o->object.type != OBJECT_DATA) {
+                        log_error("Compressed non-data object at %llu", (unsigned long long) p);
+                        r = -EBADMSG;
+                        goto fail;
+                }
+
+                if (o->object.type == OBJECT_TAG) {
+
+                        if (!(le32toh(f->header->compatible_flags) & HEADER_COMPATIBLE_AUTHENTICATED)) {
+                                log_error("Tag object without authentication at %llu", (unsigned long long) p);
+                                r = -EBADMSG;
+                                goto fail;
+                        }
+
+                        if (le64toh(o->tag.seqnum) != tag_seqnum) {
+                                log_error("Tag sequence number out of synchronization at %llu", (unsigned long long) p);
+                                r = -EBADMSG;
+                                goto fail;
+                        }
+
+                } else if (o->object.type == OBJECT_ENTRY) {
+
+                        if (!entry_seqnum_set &&
+                            le64toh(o->entry.seqnum) != le64toh(f->header->head_entry_seqnum)) {
+                                log_error("Head entry sequence number incorrect");
+                                r = -EBADMSG;
+                                goto fail;
+                        }
+
+                        if (entry_seqnum_set &&
+                            entry_seqnum >= le64toh(o->entry.seqnum)) {
+                                log_error("Entry sequence number out of synchronization at %llu", (unsigned long long) p);
+                                r = -EBADMSG;
+                                goto fail;
+                        }
+
+                        entry_seqnum = le64toh(o->entry.seqnum);
+                        entry_seqnum_set = true;
+
+                        if (entry_monotonic_set &&
+                            sd_id128_equal(entry_boot_id, o->entry.boot_id) &&
+                            entry_monotonic > le64toh(o->entry.monotonic)) {
+                                log_error("Entry timestamp out of synchronization at %llu", (unsigned long long) p);
+                                r = -EBADMSG;
+                                goto fail;
+                        }
+
+                        entry_monotonic = le64toh(o->entry.monotonic);
+                        entry_boot_id = o->entry.boot_id;
+                        entry_monotonic_set = true;
+
+                        if (!entry_realtime_set &&
+                            le64toh(o->entry.realtime) != le64toh(f->header->head_entry_realtime)) {
+                                log_error("Head entry realtime timestamp incorrect");
+                                r = -EBADMSG;
+                                goto fail;
+                        }
+
+                        entry_realtime = le64toh(o->entry.realtime);
+                        entry_realtime_set = true;
+
+                        n_entries ++;
+                } else if (o->object.type == OBJECT_ENTRY_ARRAY) {
+
+                        if (p == le64toh(f->header->entry_array_offset)) {
+                                if (found_main_entry_array) {
+                                        log_error("More than one main entry array at %llu", (unsigned long long) p);
+                                        r = -EBADMSG;
+                                        goto fail;
+                                }
+
+                                found_main_entry_array = true;
+                        }
+
+                } else if (o->object.type == OBJECT_DATA)
+                        n_data++;
+                else if (o->object.type == OBJECT_FIELD)
+                        n_fields++;
+                else if (o->object.type == OBJECT_DATA_HASH_TABLE) {
+                        n_data_hash_tables++;
+
+                        if (n_data_hash_tables > 1) {
+                                log_error("More than one data hash table at %llu", (unsigned long long) p);
+                                r = -EBADMSG;
+                                goto fail;
+                        }
+
+                        if (le64toh(f->header->data_hash_table_offset) != p + offsetof(HashTableObject, items) ||
+                            le64toh(f->header->data_hash_table_size) != le64toh(o->object.size) - offsetof(HashTableObject, items)) {
+                                log_error("Header fields for data hash table invalid.");
+                                r = -EBADMSG;
+                                goto fail;
+                        }
+                } else if (o->object.type == OBJECT_FIELD_HASH_TABLE) {
+                        n_field_hash_tables++;
+
+                        if (n_field_hash_tables > 1) {
+                                log_error("More than one field hash table at %llu", (unsigned long long) p);
+                                r = -EBADMSG;
+                                goto fail;
+                        }
+
+                        if (le64toh(f->header->field_hash_table_offset) != p + offsetof(HashTableObject, items) ||
+                            le64toh(f->header->field_hash_table_size) != le64toh(o->object.size) - offsetof(HashTableObject, items)) {
+                                log_error("Header fields for field hash table invalid.");
+                                r = -EBADMSG;
+                                goto fail;
+                        }
+                }
+
+                if (o->object.type >= _OBJECT_TYPE_MAX)
+                        n_weird ++;
+                else {
+                        /* Write address to file... */
+
+                }
+
+                if (p == le64toh(f->header->tail_object_offset))
+                        p = 0;
+                else
+                        p = p + ALIGN64(le64toh(o->object.size));
+        }
+
+        if (n_objects != le64toh(f->header->n_objects)) {
+                log_error("Object number mismatch");
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        if (n_entries != le64toh(f->header->n_entries)) {
+                log_error("Entry number mismatch");
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_data) &&
+            n_data != le64toh(f->header->n_data)) {
+                log_error("Data number mismatch");
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_fields) &&
+            n_fields != le64toh(f->header->n_fields)) {
+                log_error("Field number mismatch");
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_tags) &&
+            tag_seqnum != le64toh(f->header->n_tags)) {
+                log_error("Tag number mismatch");
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        if (n_data_hash_tables != 1) {
+                log_error("Missing data hash table");
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        if (n_field_hash_tables != 1) {
+                log_error("Missing field hash table");
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        if (!found_main_entry_array) {
+                log_error("Missing entry array");
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        if (entry_seqnum_set &&
+            entry_seqnum != le64toh(f->header->tail_entry_seqnum)) {
+                log_error("Invalid tail seqnum");
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        if (entry_monotonic_set &&
+            (!sd_id128_equal(entry_boot_id, f->header->boot_id) ||
+             entry_monotonic != le64toh(f->header->tail_entry_monotonic))) {
+                log_error("Invalid tail monotonic timestamp");
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        if (entry_realtime_set && entry_realtime != le64toh(f->header->tail_entry_realtime)) {
+                log_error("Invalid tail realtime timestamp");
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        /* Second iteration: we go through all objects again, this
+         * time verify all pointers. */
+
+        /* q = le64toh(f->header->header_size); */
+        /* while (q != 0) { */
+        /*         r = journal_file_move_to_object(f, -1, q, &o); */
+        /*         if (r < 0) { */
+        /*                 log_error("Invalid object at %llu", (unsigned long long) q); */
+        /*                 goto fail; */
+        /*         } */
+
+        /*         if (q == le64toh(f->header->tail_object_offset)) */
+        /*                 q = 0; */
+        /*         else */
+        /*                 q = q + ALIGN64(le64toh(o->object.size)); */
+        /* } */
+
+        flush_progress();
+
+        return 0;
+
+fail:
+        e = p <= 0 ? q :
+        q <= 0 ? p :
+        MIN(p, q);
+
+        flush_progress();
+
+        log_error("File corruption detected at %s:%llu (of %llu, %llu%%).",
+                  f->path,
+                  (unsigned long long) e,
+                  (unsigned long long) f->last_stat.st_size,
+                  (unsigned long long) (100 * e / f->last_stat.st_size));
+
+        return r;
+}
+
 void journal_file_dump(JournalFile *f) {
         Object *o;
         int r;
@@ -2331,8 +2734,8 @@ void journal_file_print_header(JournalFile *f) {
                (unsigned long long) le64toh(f->header->n_objects),
                (unsigned long long) le64toh(f->header->n_entries),
                yes_no(journal_file_rotate_suggested(f)),
-               (unsigned long long) le64toh(f->header->head_seqnum),
-               (unsigned long long) le64toh(f->header->tail_seqnum),
+               (unsigned long long) le64toh(f->header->head_entry_seqnum),
+               (unsigned long long) le64toh(f->header->tail_entry_seqnum),
                format_timestamp(x, sizeof(x), le64toh(f->header->head_entry_realtime)),
                format_timestamp(y, sizeof(y), le64toh(f->header->tail_entry_realtime)));
 
@@ -2536,7 +2939,7 @@ int journal_file_rotate(JournalFile **f, bool compress, bool authenticate) {
         sd_id128_to_string(old_file->header->seqnum_id, p + l - 8 + 1);
         snprintf(p + l - 8 + 1 + 32, 1 + 16 + 1 + 16 + 8 + 1,
                  "-%016llx-%016llx.journal",
-                 (unsigned long long) le64toh((*f)->header->tail_seqnum),
+                 (unsigned long long) le64toh((*f)->header->tail_entry_seqnum),
                  (unsigned long long) le64toh((*f)->header->tail_entry_realtime));
 
         r = rename(old_file->path, p);
diff --git a/src/journal/journal-file.h b/src/journal/journal-file.h
index 11a1c7d641..0305c97134 100644
--- a/src/journal/journal-file.h
+++ b/src/journal/journal-file.h
@@ -150,3 +150,5 @@ int journal_file_get_cutoff_monotonic_usec(JournalFile *f, sd_id128_t boot, usec
 bool journal_file_rotate_suggested(JournalFile *f);
 
 int journal_file_append_tag(JournalFile *f);
+
+int journal_file_verify(JournalFile *f, const char *key);
diff --git a/src/journal/journalctl.c b/src/journal/journalctl.c
index b4874a77be..8e09ff115a 100644
--- a/src/journal/journalctl.c
+++ b/src/journal/journalctl.c
@@ -62,7 +62,8 @@ static enum {
         ACTION_SHOW,
         ACTION_NEW_ID128,
         ACTION_PRINT_HEADER,
-        ACTION_SETUP_KEYS
+        ACTION_SETUP_KEYS,
+        ACTION_VERIFY
 } arg_action = ACTION_SHOW;
 
 static int help(void) {
@@ -86,7 +87,8 @@ static int help(void) {
                "Commands:\n"
                "     --new-id128      Generate a new 128 Bit ID\n"
                "     --header         Show journal header information\n"
-               "     --setup-keys     Generate new FSPRG key pair\n",
+               "     --setup-keys     Generate new FSPRG key pair\n"
+               "     --verify         Verify journal file consistency\n",
                program_invocation_short_name);
 
         return 0;
@@ -100,7 +102,8 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_NO_TAIL,
                 ARG_NEW_ID128,
                 ARG_HEADER,
-                ARG_SETUP_KEYS
+                ARG_SETUP_KEYS,
+                ARG_VERIFY
         };
 
         static const struct option options[] = {
@@ -120,6 +123,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "header",    no_argument,       NULL, ARG_HEADER    },
                 { "priority",  no_argument,       NULL, 'p'           },
                 { "setup-keys",no_argument,       NULL, ARG_SETUP_KEYS},
+                { "verify",    no_argument,       NULL, ARG_VERIFY    },
                 { NULL,        0,                 NULL, 0             }
         };
 
@@ -203,6 +207,10 @@ static int parse_argv(int argc, char *argv[]) {
                         arg_action = ACTION_SETUP_KEYS;
                         break;
 
+                case ARG_VERIFY:
+                        arg_action = ACTION_VERIFY;
+                        break;
+
                 case 'p': {
                         const char *dots;
 
@@ -572,6 +580,27 @@ finish:
 #endif
 }
 
+static int verify(sd_journal *j) {
+        int r = 0;
+        Iterator i;
+        JournalFile *f;
+
+        assert(j);
+
+        HASHMAP_FOREACH(f, j->files, i) {
+                int k;
+
+                k = journal_file_verify(f, NULL);
+                if (k < 0) {
+                        log_warning("FAIL: %s (%s)", f->path, strerror(-k));
+                        r = -r;
+                } else
+                        log_info("PASS: %s", f->path);
+        }
+
+        return r;
+}
+
 int main(int argc, char *argv[]) {
         int r;
         sd_journal *j = NULL;
@@ -598,11 +627,6 @@ int main(int argc, char *argv[]) {
                 goto finish;
         }
 
-#ifdef HAVE_ACL
-        if (!arg_quiet && geteuid() != 0 && in_group("adm") <= 0)
-                log_warning("Showing user generated messages only. Users in the group 'adm' can see all messages. Pass -q to turn this message off.");
-#endif
-
         if (arg_directory)
                 r = sd_journal_open_directory(&j, arg_directory, 0);
         else
@@ -613,12 +637,22 @@ int main(int argc, char *argv[]) {
                 goto finish;
         }
 
+        if (arg_action == ACTION_VERIFY) {
+                r = verify(j);
+                goto finish;
+        }
+
         if (arg_action == ACTION_PRINT_HEADER) {
                 journal_print_header(j);
                 r = 0;
                 goto finish;
         }
 
+#ifdef HAVE_ACL
+        if (!arg_quiet && geteuid() != 0 && in_group("adm") <= 0)
+                log_warning("Showing user generated messages only. Users in the group 'adm' can see all messages. Pass -q to turn this message off.");
+#endif
+
         r = add_this_boot(j);
         if (r < 0)
                 goto finish;
diff --git a/src/journal/mmap-cache.c b/src/journal/mmap-cache.c
index 68dbe7015b..77710ff9bf 100644
--- a/src/journal/mmap-cache.c
+++ b/src/journal/mmap-cache.c
@@ -232,7 +232,6 @@ MMapCache* mmap_cache_new(unsigned contexts_max, unsigned fds_max) {
                 mmap_cache_free(m);
                 return NULL;
         }
-
         memset(m->by_context, -1, m->contexts_max * sizeof(unsigned));
 
         m->by_fd = new(FileDescriptor, m->fds_max);
@@ -334,7 +333,7 @@ static int mmap_cache_put(
         if (wsize < WINDOW_SIZE) {
                 uint64_t delta;
 
-                delta = (WINDOW_SIZE - wsize) / 2;
+                delta = PAGE_ALIGN((WINDOW_SIZE - wsize) / 2);
 
                 if (delta > offset)
                         woffset = 0;