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flashrom: Check for flash access restricitons in write_flash()

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Make write_flash() skip unwritable regions if
FLASHROM_FLAG_SKIP_UNWRITABLE_REGIONS is true. If the flag is false
write operations that include an unwritable region will not write
anything and return an error.

BUG=b:260440773
BRANCH=none
TEST=flashrom -w on dedede (JSL)

Change-Id: Idacf0d5218da9d9929f4877fc7665fe608b87fe0
CoAuthored-by: Edward O'Callaghan <quasisec@google.com>
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Signed-off-by: Nikolai Artemiev <nartemiev@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/70516
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Nikolai Artemiev 2022-12-09 15:28:18 +11:00 committed by Edward O'Callaghan
parent 0f389aea9e
commit ff5beeef40
1 changed files with 67 additions and 3 deletions
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70
flashrom.c
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@ -374,6 +374,23 @@ static void get_flash_region(const struct flashctx *flash, int addr, struct flas
}
}
static int check_for_unwritable_regions(const struct flashctx *flash, unsigned int start, unsigned int len)
{
struct flash_region region;
for (unsigned int addr = start; addr < start + len; addr = region.end) {
get_flash_region(flash, addr, &region);
if (region.write_prot) {
msg_gerr("%s: cannot write/erase inside %s region (%#08x..%#08x).\n",
__func__, region.name, region.start, region.end - 1);
free(region.name);
return -1;
}
free(region.name);
}
return 0;
}
/* special unit-test hook */
erasefunc_t *g_test_erase_injector;
@ -966,10 +983,57 @@ static write_func_t *lookup_write_func_ptr(const struct flashchip *chip)
return NULL;
}
static int write_flash(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
/*
* write_flash - wrapper for flash->write() with additional high-level policy
*
* @param flash flash chip
* @param buf buffer to write to flash
* @param start start address in flash
* @param len number of bytes to write
* @return 0 on success,
* -1 if any write fails.
*
* This wrapper simplifies most cases when the flash chip needs to be written
* since policy decisions such as non-fatal error handling is centralized.
*/
static int write_flash(struct flashctx *flash, const uint8_t *buf,
unsigned int start, unsigned int len)
{
write_func_t *write_func = lookup_write_func_ptr(flash->chip);
return write_func(flash, buf, start, len);
if (!flash->flags.skip_unwritable_regions) {
if (check_for_unwritable_regions(flash, start, len))
return -1;
}
unsigned int write_len;
for (unsigned int addr = start; addr < start + len; addr += write_len) {
struct flash_region region;
get_flash_region(flash, addr, &region);
write_len = min(start + len, region.end) - addr;
const uint8_t *rbuf = buf + addr - start;
if (region.write_prot) {
msg_gdbg("%s: cannot write inside %s region (%#08x..%#08x), skipping (%#08x..%#08x).\n",
__func__, region.name, region.start, region.end - 1, addr, addr + write_len - 1);
free(region.name);
continue;
}
msg_gdbg("%s: %s region (%#08x..%#08x) is writable, writing range (%#08x..%#08x).\n",
__func__, region.name, region.start, region.end - 1, addr, addr + write_len - 1);
write_func_t *write_func = lookup_write_func_ptr(flash->chip);
int ret = write_func(flash, rbuf, addr, write_len);
if (ret) {
msg_gerr("%s: failed to write (%#08x..%#08x).\n", __func__, addr, addr + write_len - 1);
free(region.name);
return -1;
}
free(region.name);
}
return 0;
}
typedef int (probe_func_t)(struct flashctx *flash);