[PATCH mtd-utils] libmtd: don't ignore "region index" parameter in mtd_regioninfo()

Brian Norris
2014-09-15T17:48:50Z

ioctl(MEMGETREGIONINFO) has one input parameter (regionindex) and three
output parameters (info about the erase region). There are two problems
in mtdinfo/libmtd here:

1. mtdinfo.c doesn't initialize its region_info_user struct, instead
passing uninitialized data to mtd_regioninfo()

2. mtd_regioninfo() fails to utilize the 'regidx' parameter to fill out
the regionindex parameter properly, so the garbage from mtdinfo.c is
propagated to the ioctl()

This means that mtdinfo will continuously probe the same (possibly
out-of-range) erase region, instead of looping over the valid regions.

Let's fix this in the mtd_regioninfo() helper, and at the same time,
let's zero out the mtdinfo.c buffer, as an additional precaution to keep
from using uninitialized data.

Initial error report from Yang, when running "mtdinfo /dev/mtd0" on a
Cavium 6100 board:

root@CN61XX:~# mtdinfo /dev/mtd0
mtd0
Name: phys_mapped_flash
Type: nor
Eraseblock size: 65536 bytes, 64.0 KiB
Amount of eraseblocks: 128 (8388608 bytes, 8.0 MiB)
Minimum input/output unit size: 1 byte
Sub-page size: 1 byte
Additional erase regions: 0
Character device major/minor: 90:0
Bad blocks are allowed: false
Device is writable: true
libmtd: error!: MEMGETREGIONINFO ioctl failed for erase region 0
error 22 (Invalid argument)
Eraseblock region 0: info is unavailable
libmtd: error!: MEMGETREGIONINFO ioctl failed for erase region 1
error 22 (Invalid argument)
Eraseblock region 1: info is unavailable

Reported-by: Yang Wei <Wei.Yang@windriver.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
---
Untested so far. Can you give this a run, Yang?

lib/libmtd.c | 2 ++
ubi-utils/mtdinfo.c | 2 ++
2 files changed, 4 insertions(+)

diff --git a/lib/libmtd.c b/lib/libmtd.c
index aff4c8be01b5..a6665f08018e 100644
--- a/lib/libmtd.c
+++ b/lib/libmtd.c
@@ -901,6 +901,8 @@ int mtd_regioninfo(int fd, int regidx, struct region_info_user *reginfo)
return -1;
}

+ reginfo->regionindex = regidx;
+
ret = ioctl(fd, MEMGETREGIONINFO, reginfo);
if (ret < 0)
return sys_errmsg("%s ioctl failed for erase region %d",
diff --git a/ubi-utils/mtdinfo.c b/ubi-utils/mtdinfo.c
index 5ac95aaabb8a..a86abd1542b4 100644
--- a/ubi-utils/mtdinfo.c
+++ b/ubi-utils/mtdinfo.c
@@ -253,6 +253,8 @@ static void print_region_info(const struct mtd_dev_info *mtd)
if (!args.node || (!args.map && mtd->region_cnt == 0))
return;

+ memset(&reginfo, 0, sizeof(reginfo));
+
/* First open the device so we can query it */
fd = open(args.node, O_RDONLY | O_CLOEXEC);
if (fd == -1) {
--
1.9.1