From ff5beeef409515d0db84f1e902388590f5b15c44 Mon Sep 17 00:00:00 2001 From: Nikolai Artemiev Date: Fri, 9 Dec 2022 15:28:18 +1100 Subject: flashrom: Check for flash access restricitons in write_flash() 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 Signed-off-by: Edward O'Callaghan Signed-off-by: Nikolai Artemiev Reviewed-on: https://review.coreboot.org/c/flashrom/+/70516 Reviewed-by: Edward O'Callaghan Reviewed-by: Angel Pons Tested-by: build bot (Jenkins) --- flashrom.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 67 insertions(+), 3 deletions(-) (limited to 'flashrom.c') diff --git a/flashrom.c b/flashrom.c index 785da6f3..b611bebc 100644 --- a/flashrom.c +++ b/flashrom.c @@ -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, ®ion); + + 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, ®ion); + + 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); -- cgit v1.2.3