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crossystem: allow last nvdata entry to be filled 

Mosys used to have code (below), which led me to believe that we
always try and leave the last entry unfilled:

        memset(blank, 0xff, VBNV_BLOCK_SIZE);
        for (index = 0; index < len / VBNV_BLOCK_SIZE; index++) {
                unsigned int offset = index * VBNV_BLOCK_SIZE;
                if (!memcmp(blank, &data[offset], VBNV_BLOCK_SIZE))
                        break;
        }

        if (index == 0) {
                lprintf(LOG_ERR, "VBNV is uninitialized\n");
                return -1;
        } else if (index >= len) {  <---- SEE NOTE
                lprintf(LOG_ERR, "VBNV is full\n");   <--- unreachable
                return -1;
        } else {
                return index - 1;
        }

The statement at "SEE NOTE" will always be false, so this code fooled
me to believe that we consider VBNV without a row of 0xFF*16 to be
empty.

And so I implemented and wrote unit tests for what I believed the
correct behavior to be :/

Anyway, this is causing us issues since AP firmware does not implement
it that way.  So allow the last row to be filled.

BUG=chromium:1112578
BRANCH=none
TEST=unit tests

Signed-off-by: Jack Rosenthal <jrosenth@chromium.org>
Change-Id: Ib3da78eddef69a688d081cdb5391a25000dac9d3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2402385
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
This commit is contained in:
Jack Rosenthal 2020-09-09 17:47:21 -06:00 committed by Commit Bot
parent 3dd8fe4c4e
commit 176e01ded3
2 changed files with 6 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
host/lib/crossystem.c
View File

@ -685,8 +685,8 @@ static int vb2_nv_index(const uint8_t *buf, uint32_t buf_sz, int vbnv_size)
break;
}
if (!index || index == buf_sz / vbnv_size) {
fprintf(stderr, "VBNV is either uninitialized or corrupted.\n");
if (!index) {
fprintf(stderr, "VBNV is uninitialized.\n");
return -1;
}
@ -737,7 +737,7 @@ int vb2_write_nv_storage_flashrom(struct vb2_context *ctx)
}
next_index = current_index + 1;
if ((next_index + 1) * vbnv_size == flash_size) {
if (next_index * vbnv_size == flash_size) {
/* VBNV is full. Erase and write at beginning. */
memset(flash_buf, 0xff, flash_size);
next_index = 0;

6
tests/vb2_host_nvdata_flashrom_tests.c
View File

@ -147,12 +147,12 @@ static void test_read_ok_full(void)
reset_test_data(&ctx, sizeof(test_nvdata_16b));
for (int entry = 0; entry < fake_flash_entry_count - 2; entry++)
for (int entry = 0; entry < fake_flash_entry_count - 1; entry++)
memcpy(fake_flash_region + (entry * VB2_NVDATA_SIZE),
test_nvdata_16b, sizeof(test_nvdata_16b));
memcpy(fake_flash_region +
((fake_flash_entry_count - 2) * VB2_NVDATA_SIZE),
((fake_flash_entry_count - 1) * VB2_NVDATA_SIZE),
test_nvdata2_16b, sizeof(test_nvdata2_16b));
TEST_EQ(vb2_read_nv_storage_flashrom(&ctx), 0,
@ -222,7 +222,7 @@ static void test_write_ok_full(void)
reset_test_data(&ctx, sizeof(test_nvdata_16b));
for (int entry = 0; entry < fake_flash_entry_count - 1; entry++)
for (int entry = 0; entry < fake_flash_entry_count; entry++)
memcpy(fake_flash_region + (entry * VB2_NVDATA_SIZE),
test_nvdata_16b, sizeof(test_nvdata_16b));