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authorDmitry Monakhov <dmonakhov@openvz.org>2011-11-16 09:21:49 +0100
committerJens Axboe <axboe@kernel.dk>2011-11-16 09:21:49 +0100
commit7035b5df3c071ccaf2f1694b96bd8958b0eb37ca (patch)
tree146e916bce5b11232afac2319c012b1fccba54d0 /Documentation
parent0c614e2d3e6ee6ff13c6181f380787cea1d82d1d (diff)
loop: cleanup set_status interface
1) Anyone who has read access to loopdev has permission to call set_status and may change important parameters such as lo_offset, lo_sizelimit and so on, which contradicts to read access pattern and definitely equals to write access pattern. 2) Add lo_offset over i_size check to prevent blkdev_size overflow. ##Testcase_bagin #dd if=/dev/zero of=./file bs=1k count=1 #losetup /dev/loop0 ./file /* userspace_application */ struct loop_info64 loinf; fd = open("/dev/loop0", O_RDONLY); ioctl(fd, LOOP_GET_STATUS64, &loinf); /* Set offset to any value which is bigger than i_size, and sizelimit * to nonzero value*/ loinf.lo_offset = 4096*1024; loinf.lo_sizelimit = 1024; ioctl(fd, LOOP_SET_STATUS64, &loinf); /* After this loop device will have size similar to 0x7fffffffffxxxx */ #blockdev --getsz /dev/loop0 ##OUTPUT: 36028797018955968 ##Testcase_end [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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