From bdd5ae00e8cf4f45183a20e5bc89efd3dcc02266 Mon Sep 17 00:00:00 2001

From: Tobias Stoeckmann <stoeckmann@users.noreply.github.com>

Date: Mon, 13 Mar 2017 08:14:42 +0100

Subject: [PATCH] journal: prevent integer overflow while validating header

 (#5569)

It is possible to overflow uint64_t while validating the header of

a journal file. To prevent this, the addition itself is checked to

be within the limits of UINT64_MAX first.

To keep this readable, I have introduced two stack variables which

hold the converted values during validation.

(cherry picked from commit 6f94e420e8355421fc31713a0df760d6b20473ac)

---

 src/journal/journal-file.c | 12 +++++++++---

 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c

index a6ccb679a8..14cb01a600 100644

--- a/src/journal/journal-file.c

+++ b/src/journal/journal-file.c

@@ -546,6 +546,8 @@ static bool warn_wrong_flags(const JournalFile *f, bool compatible) {

 }

 static int journal_file_verify_header(JournalFile *f) {

+        uint64_t arena_size, header_size;

+

         assert(f);

         assert(f->header);

@@ -564,17 +566,21 @@ static int journal_file_verify_header(JournalFile *f) {

         if (f->header->state >= _STATE_MAX)

                 return -EBADMSG;

+        header_size = le64toh(f->header->header_size);

+

         /* The first addition was n_data, so check that we are at least this large */

-        if (le64toh(f->header->header_size) < HEADER_SIZE_MIN)

+        if (header_size < HEADER_SIZE_MIN)

                 return -EBADMSG;

         if (JOURNAL_HEADER_SEALED(f->header) && !JOURNAL_HEADER_CONTAINS(f->header, n_entry_arrays))

                 return -EBADMSG;

-        if ((le64toh(f->header->header_size) + le64toh(f->header->arena_size)) > (uint64_t) f->last_stat.st_size)

+        arena_size = le64toh(f->header->arena_size);

+

+        if (UINT64_MAX - header_size < arena_size || header_size + arena_size > (uint64_t) f->last_stat.st_size)

                 return -ENODATA;

-        if (le64toh(f->header->tail_object_offset) > (le64toh(f->header->header_size) + le64toh(f->header->arena_size)))

+        if (le64toh(f->header->tail_object_offset) > header_size + arena_size)

                 return -ENODATA;

         if (!VALID64(le64toh(f->header->data_hash_table_offset)) ||