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authorLoic Poulain <loic.poulain@linaro.org>2023-05-10 09:42:23 +0200
committerJens Axboe <axboe@kernel.dk>2023-05-20 04:17:10 +0200
commit69baa3a623fd2e58624f24f2f23d46f87b817c93 (patch)
treec12d32ab13e9a1283dcb8701fd3f2065b06255e4 /block/holder.c
parents390/dasd: fix command reject error on ESE devices (diff)
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block: Deny writable memory mapping if block is read-only
User should not be able to write block device if it is read-only at block level (e.g force_ro attribute). This is ensured in the regular fops write operation (blkdev_write_iter) but not when writing via user mapping (mmap), allowing user to actually write a read-only block device via a PROT_WRITE mapping. Example: This can lead to integrity issue of eMMC boot partition (e.g mmcblk0boot0) which is read-only by default. To fix this issue, simply deny shared writable mapping if the block is readonly. Note: Block remains writable if switch to read-only is performed after the initial mapping, but this is expected behavior according to commit a32e236eb93e ("Partially revert "block: fail op_is_write() requests to read-only partitions"")'. Signed-off-by: Loic Poulain <loic.poulain@linaro.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20230510074223.991297-1-loic.poulain@linaro.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/holder.c')
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