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lib-index: mail-index-sync-ext - Fix offset overflow in ext header update #303

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lib-index: mail-index-sync-ext - Fix offset overflow in ext header update #303

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2 changes: 1 addition & 1 deletion src/lib-index/mail-index-sync-ext.c
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Original file line number Diff line number Diff line change
Expand Up @@ -585,7 +585,7 @@ int mail_index_sync_ext_hdr_update(struct mail_index_sync_map_ctx *ctx,
return 1;

ext = array_idx(&map->extensions, ctx->cur_ext_map_idx);
if (offset + size > ext->hdr_size) {
if (offset > ext->hdr_size || size > ext->hdr_size - offset) {
mail_index_sync_set_corrupted(ctx,
"Extension header update points outside header size");
return -1;
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46 changes: 46 additions & 0 deletions src/lib-index/test-mail-index-sync-ext.c
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Original file line number Diff line number Diff line change
Expand Up @@ -76,10 +76,56 @@ static void test_mail_index_sync_ext_atomic_inc(void)
test_end();
}

static void test_mail_index_sync_ext_hdr_update(void)
{
struct mail_index_sync_map_ctx ctx;
struct mail_index_ext *ext;
unsigned char data[8] = { 1, 2, 3, 4, 5, 6, 7, 8 };

test_begin("mail index sync ext hdr update");

i_zero(&ctx);
ctx.view = t_new(struct mail_index_view, 1);
ctx.view->log_view = t_new(struct mail_transaction_log_view, 1);
ctx.view->index = t_new(struct mail_index, 1);
ctx.view->index->fsck_log_head_file_seq = 10; /* silence errors */
ctx.view->map = t_new(struct mail_index_map, 1);
ctx.view->map->hdr.header_size = 64;
ctx.view->map->hdr_copy_buf = buffer_create_dynamic(default_pool, 64);
buffer_append_zero(ctx.view->map->hdr_copy_buf, 64);

t_array_init(&ctx.view->map->extensions, 4);
ext = array_append_space(&ctx.view->map->extensions);
ext->index_idx = 5; /* != modseq_ext_id (0), skip modseq handling */
ext->hdr_offset = 16;
ext->hdr_size = 8;

ctx.cur_ext_map_idx = 0;

/* valid updates within the extension header */
test_assert(mail_index_sync_ext_hdr_update(&ctx, 0, 8, data) == 1);
test_assert(mail_index_sync_ext_hdr_update(&ctx, 4, 4, data) == 1);

/* ordinary out-of-range update is rejected */
test_assert(mail_index_sync_ext_hdr_update(&ctx, 4, 8, data) == -1);

/* offset+size wraps around 2^32 and must not pass the bounds check:
0xfffffff8 + 8 == 0, which is <= hdr_size */
test_assert(mail_index_sync_ext_hdr_update(&ctx, 0xfffffff8, 8,
data) == -1);
test_assert(mail_index_sync_ext_hdr_update(&ctx, 0xffffffff, 1,
data) == -1);

buffer_free(&ctx.view->map->hdr_copy_buf);
i_free(ctx.view->index->need_recreate);
test_end();
}

int main(void)
{
static void (*const test_functions[])(void) = {
test_mail_index_sync_ext_atomic_inc,
test_mail_index_sync_ext_hdr_update,
NULL
};
return test_run(test_functions);
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