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Subject[PATCH] md: fix missing check on list iterator
Date
The bug is here:
bypass_pg(m, pg, bypassed);

The list iterator 'pg' will point to a bogus position containing
HEAD if the list is empty or no element is found. This case must
be checked before any use of the iterator, otherwise it will lead
to a invalid memory access.

To fix this bug, run bypass_pg(m, pg, bypassed); and return 0
when found, otherwise return -EINVAL.

Cc: stable@vger.kernel.org
Fixes: ^1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
---
drivers/md/dm-mpath.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index f4719b65e5e3..6ba8f1133564 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1496,12 +1496,13 @@ static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
}

list_for_each_entry(pg, &m->priority_groups, list) {
- if (!--pgnum)
- break;
+ if (!--pgnum) {
+ bypass_pg(m, pg, bypassed);
+ return 0;
+ }
}

- bypass_pg(m, pg, bypassed);
- return 0;
+ return -EINVAL;
}

/*
--
2.17.1
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