[PATCH 5.4 385/434] md: avoid invalid memory access for array sb->dev_roles

Greg Kroah-Hartman
2019-12-29T17:56:50Z

From: Yufen Yu <yuyufen@huawei.com>

[ Upstream commit 228fc7d76db68732677230a3c64337908fd298e3 ]

we need to gurantee 'desc_nr' valid before access array
of sb->dev_roles.

In addition, we should avoid .load_super always return '0'
when level is LEVEL_MULTIPATH, which is not expected.

Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1487373 ("Memory - illegal accesses")
Fixes: 6a5cb53aaa4e ("md: no longer compare spare disk superblock events in super_load")
Signed-off-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/md.c | 51 +++++++++++++++++++------------------------------
1 file changed, 20 insertions(+), 31 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 6f0ecfe8eab2..805b33e27496 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1105,6 +1105,7 @@ static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor
char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
mdp_super_t *sb;
int ret;
+ bool spare_disk = true;

/*
* Calculate the position of the superblock (512byte sectors),
@@ -1155,13 +1156,15 @@ static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor
else
rdev->desc_nr = sb->this_disk.number;

+ /* not spare disk, or LEVEL_MULTIPATH */
+ if (sb->level == LEVEL_MULTIPATH ||
+ (rdev->desc_nr >= 0 &&
+ sb->disks[rdev->desc_nr].state &
+ ((1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE))))
+ spare_disk = false;
+
if (!refdev) {
- /*
- * Insist on good event counter while assembling, except
- * for spares (which don't need an event count)
- */
- if (sb->disks[rdev->desc_nr].state & (
- (1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)))
+ if (!spare_disk)
ret = 1;
else
ret = 0;
@@ -1181,13 +1184,7 @@ static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor
ev1 = md_event(sb);
ev2 = md_event(refsb);

- /*
- * Insist on good event counter while assembling, except
- * for spares (which don't need an event count)
- */
- if (sb->disks[rdev->desc_nr].state & (
- (1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)) &&
- (ev1 > ev2))
+ if (!spare_disk && ev1 > ev2)
ret = 1;
else
ret = 0;
@@ -1547,7 +1544,7 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_
sector_t sectors;
char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
int bmask;
- __u64 role;
+ bool spare_disk = true;

/*
* Calculate the position of the superblock in 512byte sectors.
@@ -1681,17 +1678,16 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_
sb->level != 0)
return -EINVAL;

- role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
+ /* not spare disk, or LEVEL_MULTIPATH */
+ if (sb->level == cpu_to_le32(LEVEL_MULTIPATH) ||
+ (rdev->desc_nr >= 0 &&
+ rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
+ (le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < MD_DISK_ROLE_MAX ||
+ le16_to_cpu(sb->dev_roles[rdev->desc_nr]) == MD_DISK_ROLE_JOURNAL)))
+ spare_disk = false;

if (!refdev) {
- /*
- * Insist of good event counter while assembling, except for
- * spares (which don't need an event count)
- */
- if (rdev->desc_nr >= 0 &&
- rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
- (role < MD_DISK_ROLE_MAX ||
- role == MD_DISK_ROLE_JOURNAL))
+ if (!spare_disk)
ret = 1;
else
ret = 0;
@@ -1711,14 +1707,7 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_
ev1 = le64_to_cpu(sb->events);
ev2 = le64_to_cpu(refsb->events);

- /*
- * Insist of good event counter while assembling, except for
- * spares (which don't need an event count)
- */
- if (rdev->desc_nr >= 0 &&
- rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
- (role < MD_DISK_ROLE_MAX ||
- role == MD_DISK_ROLE_JOURNAL) && ev1 > ev2)
+ if (!spare_disk && ev1 > ev2)
ret = 1;
else
ret = 0;
--
2.20.1