From b83c64f7a12538417649accc1269c22d5ff074bb Mon Sep 17 00:00:00 2001 From: Enrico Jorns Date: Fri, 19 Aug 2022 14:32:13 +0200 Subject: libmtd: do not ignore non-zero eraseblock size when MTD_NO_ERASE is set In 54d68799, mtd->eb_cnt was enforced to be '1' if MTD_NO_ERASE is set. This was done with the aim of preventing divisions by zero. However, even if MTD_NO_ERASE is set, mtd->eb_size (eraseblock size) can still be set to a non-zero value which would not cause a division by zero. Instead, enforcing an eraseblock count of '1' here even leads to inconsistent eraseblock counting in mtd-utils and lets for example a 'flash_erase' on an mtdnand device fail: | # flash_erase /dev/mtd0 0 0 | Erasing 32768 Kibyte @ 0 -- 0 % complete libmtd: error!: bad eraseblock number 255, mtd0 has 1 eraseblocks | flash_erase: error!: /dev/mtd0: MTD Erase entire chip failureTrying one by one each sector. | error 22 (Invalid argument) | Erasing 128 Kibyte @ 0 -- 0 % complete libmtd: error!: bad eraseblock number 1, mtd0 has 1 eraseblocks | flash_erase: error!: /dev/mtd0: MTD get bad block failed | error 22 (Invalid argument) Also mtdinfo would look inconsistent (eraseblock size vs amount): | # mtdinfo /dev/mtd0 | mtd0 | Name: mtdram test device | Type: ram | Eraseblock size: 131072 bytes, 128.0 KiB | Amount of eraseblocks: 1 (33554432 bytes, 32.0 MiB) | Minimum input/output unit size: 1 byte | Sub-page size: 1 byte | Character device major/minor: 90:0 | Bad blocks are allowed: false | Device is writable: true Fix this by enforcing mtd->eb_cnt to be '1' only when mtd->eb_size is actually zero and would lead to a division by zero otherwise. Fixes: 54d68799 ("libmtd: avoid divide by zero") Signed-off-by: Enrico Jorns Signed-off-by: David Oberhollenzer --- lib/libmtd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/libmtd.c b/lib/libmtd.c index a363e56..4aee947 100644 --- a/lib/libmtd.c +++ b/lib/libmtd.c @@ -792,7 +792,7 @@ int mtd_get_dev_info1(libmtd_t desc, int mtd_num, struct mtd_dev_info *mtd) return -1; mtd->writable = !!(ret & MTD_WRITEABLE); - if (ret & MTD_NO_ERASE) + if ((ret & MTD_NO_ERASE) && (mtd->eb_size == 0)) mtd->eb_cnt = 1; else mtd->eb_cnt = mtd->size / mtd->eb_size; -- cgit v1.2.3