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dm table: fix invalid memory accesses with too high sector number 

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.

Fix this bug by testing the sector number at the beginning of
dm_table_find_target(). Also, add an "inline" keyword to the function
dm_table_get_size() because this is a hot path.

Fixes: 512875bd96 ("dm: table detect io beyond device")
Cc: stable@vger.kernel.org
Reported-by: Zhang Tao <kontais@zoho.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka 2019-08-23 09:54:09 -04:00 committed by Mike Snitzer
parent ae148243d3
commit 1cfd5d3399
1 changed files with 4 additions and 1 deletions
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5
drivers/md/dm-table.c
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@ -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(struct dm_table *t, sector_t sector)
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);