[PATCH] nvdimm: add extra LBA check for map read and write operations

[Dmitry Antipov]

In 'btt_map_read()' and '__btt_map_write()', add an extra check
whether requested LBA may be represented as valid offset against
an offset of the map area of the given arena. Compile tested only.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Dmitry Antipov <dmanti...@yandex.ru>
---
 drivers/nvdimm/btt.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 423dcd190906..2bd03143c8c3 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -96,12 +96,17 @@ static int btt_info_read(struct arena_info *arena, struct 
btt_sb *super)
 static int __btt_map_write(struct arena_info *arena, u32 lba, __le32 mapping,
                unsigned long flags)
 {
-       u64 ns_off = arena->mapoff + (lba * MAP_ENT_SIZE);
+       u32 lba_off;
+       u64 ns_off;
 
-       if (unlikely(lba >= arena->external_nlba))
+       if (unlikely(lba >= arena->external_nlba ||
+                    check_mul_overflow(lba, MAP_ENT_SIZE, &lba_off)))
                dev_err_ratelimited(to_dev(arena),
                        "%s: lba %#x out of range (max: %#x)\n",
                        __func__, lba, arena->external_nlba);
+
+       ns_off = arena->mapoff + lba_off;
+
        return arena_write_bytes(arena, ns_off, &mapping, MAP_ENT_SIZE, flags);
 }
 
@@ -154,14 +159,17 @@ static int btt_map_read(struct arena_info *arena, u32 
lba, u32 *mapping,
 {
        int ret;
        __le32 in;
-       u32 raw_mapping, postmap, ze, z_flag, e_flag;
-       u64 ns_off = arena->mapoff + (lba * MAP_ENT_SIZE);
+       u64 ns_off;
+       u32 raw_mapping, postmap, ze, z_flag, e_flag, lba_off;
 
-       if (unlikely(lba >= arena->external_nlba))
+       if (unlikely(lba >= arena->external_nlba ||
+                    check_mul_overflow(lba, MAP_ENT_SIZE, &lba_off)))
                dev_err_ratelimited(to_dev(arena),
                        "%s: lba %#x out of range (max: %#x)\n",
                        __func__, lba, arena->external_nlba);
 
+       ns_off = arena->mapoff + lba_off;
+
        ret = arena_read_bytes(arena, ns_off, &in, MAP_ENT_SIZE, rwb_flags);
        if (ret)
                return ret;
-- 
2.47.1