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Benjamin MarzinskiandYury Norov
1c61b0a6e5
The *_bit_le functions use a signed integer for the bit number. However, the *_bit functions can use an unsigned long. This causes problems if there is a large bitmap and a bit number > 0x80000000 is passed in. Since that is a negative int, it will get sign extended to a long when getting passed to the *_bit function, turning it into a huge bit number. This usually ends up with the memory address wrapping around and the function accessing memory before the start of the bitmap. Avoid this by making the *_bit_le functions take an unsigned long. This can be triggered by faking an almost 4TB dm-mirror device, which uses bitmaps to track the mirror regions: $ dmsetup create bigzero --table '0 8589934590 zero' $ dmsetup create mymirror --table '0 8589934590 mirror core 2 2 nosync 2 /dev/mapper/bigzero 0 /dev/mapper/bigzero 0' This will access memory before the start of the sync_bits bitmap, and likely hit the guard page of the previously allocated clean_bits bitmap, causing a kernel panic with the old code. I looked and didn't see any crazy code using the signed int to intentionally try and access bits before some address within the bitmap. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Yury Norov <ynorov@nvidia.com>