forked from pool/util-linux
101 lines
2.9 KiB
Diff
101 lines
2.9 KiB
Diff
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From 445e6b1ec82642a298419bdd18a81110593bfbaa Mon Sep 17 00:00:00 2001
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From: Petr Uzel <petr.uzel@suse.cz>
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Date: Mon, 18 Apr 2016 16:22:05 +0200
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Subject: [PATCH] libblkid: make blkid_do_wipe() work with probes with offset
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When a probe is created with an offset, e.g. via
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blkid_probe_set_device(), this offset is correctly used when looking for
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the signatures, but is not respected by blkid_do_wipe() function.
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Therefore the signature is removed from an invalid location.
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Usecase: Wiping signatures from an area on the block device where
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partition is to be created (but as it does not exist yet, there's no
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device node for it and probe on the whole block device has to be used
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with correct offset and length).
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Reproducer:
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======================== wiper.c ===========================
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const char *dev;
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unsigned long offset;
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unsigned long size;
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int main(int argc, char** argv) {
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if (argc != 4) {
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printf("usage: wiper dev offset size\n");
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exit(1);
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}
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dev = argv[1];
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offset = strtoull(argv[2], NULL, 10);
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size = strtoull(argv[3], NULL, 10);
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printf("dev=%s, off=%llu, size=%llu\n", dev, offset, size);
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int fd = open (dev, O_RDWR);
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if (fd == -1) {
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perror("open");
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exit(1);
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}
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blkid_loff_t wipe_offset = offset * SECTOR_SIZE;
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blkid_loff_t wipe_size = size * SECTOR_SIZE;
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int ret;
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blkid_probe pr;
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pr = blkid_new_probe();
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if (!pr)
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return 0;
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ret = blkid_probe_set_device(pr, fd, wipe_offset, wipe_size);
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ret = blkid_probe_enable_superblocks(pr, 1);
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ret = blkid_probe_set_superblocks_flags(pr, BLKID_SUBLKS_MAGIC);
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while (blkid_do_probe(pr) == 0) {
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ret = blkid_do_wipe(pr, 0);
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}
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blkid_free_probe(pr);
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close(fd);
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}
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======================== wiper.c ===========================
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Steps to reproduce:
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modprobe scsi_debug
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parted -s /dev/sdX mklabel gpt
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parted -s /dev/sdX mkpart first 2048s 4095s
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mkfs.ext2 /dev/sdX1
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wipefs -np /dev/sdX1
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./wiper /dev/sdX1 2048 2048
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Actual result: wiper gets into endless loop, because
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blkid_do_wipe() wipes at wrong location (1080), leaving the signature
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on /dev/sdc1. So it is again found by blkid_do_probe(), and so on.
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Expected result: wiper clears the ext2 signature at offset 1049656(=1080+2048*512).
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Signed-off-by: Petr Uzel <petr.uzel@suse.cz>
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---
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libblkid/src/probe.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/libblkid/src/probe.c b/libblkid/src/probe.c
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index 34d97b8..0c8625c 100644
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--- a/libblkid/src/probe.c
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+++ b/libblkid/src/probe.c
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@@ -1121,7 +1121,7 @@ int blkid_do_wipe(blkid_probe pr, int dryrun)
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if (rc || len == 0 || off == NULL)
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return 0;
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- offset = strtoumax(off, NULL, 10);
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+ offset = strtoumax(off, NULL, 10) + pr->off;
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fd = blkid_probe_get_fd(pr);
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if (fd < 0)
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return -1;
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--
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2.8.1
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