If the sector number is too high, dm_table_find_target should return a
pointer to a zeroed dm_target structure (the caller should test it with
dm_target_is_valid).
However, for some table sizes, the code in dm_table_find_target that
performs btree lookup will access out of bound memory structures.
This patch fixes the bug by testing the sector number at the beginning of
dm_table_find_target. We add an "inline" keyword to the function
dm_table_get_size because this is hot path.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Reported-by: Zhang Tao <kontais@xxxxxxxx>
Fixes: 512875bd9661 ("dm: table detect io beyond device")
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/md/dm-table.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
Index: linux-2.6/drivers/md/dm-table.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-table.c 2019-08-23 13:40:51.000000000 +0200
+++ linux-2.6/drivers/md/dm-table.c 2019-08-23 15:43:19.000000000 +0200
@@ -1342,7 +1342,7 @@ void dm_table_event(struct dm_table *t)
}
EXPORT_SYMBOL(dm_table_event);
-sector_t dm_table_get_size(struct dm_table *t)
+inline sector_t dm_table_get_size(struct dm_table *t)
{
return t->num_targets ? (t->highs[t->num_targets - 1] + 1) : 0;
}
@@ -1367,6 +1367,9 @@ struct dm_target *dm_table_find_target(s
unsigned int l, n = 0, k = 0;
sector_t *node;
+ if (unlikely(sector >= dm_table_get_size(t)))
+ return &t->targets[t->num_targets];
+
for (l = 0; l < t->depth; l++) {
n = get_child(n, k);
node = get_node(t, l, n);
--
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