Integer underflow in efipart_realstrategy when I/O starts after end of disk
This fixes an integer underflow in efipart_realstrategy, which causes crashes when an I/O operation's start point is after the end of the disk. This can happen when trying to detect filesystems on very small disks. This can occur if a BIOS freebsd-boot partition exists on a system when the EFI loader is being used. PR: 219000 Submitted by: Eric McCorkle <eric@metricspace.net> Reviewed by: cem (previous version), tsoome (previous version) MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D10559
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=320553
@ -888,6 +888,7 @@ efipart_realstrategy(void *devdata, int rw, daddr_t blk, size_t size,
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char *blkbuf;
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size_t blkoff, blksz;
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int error;
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size_t diskend, readstart;
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if (dev == NULL || blk < 0)
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return (EINVAL);
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@ -925,7 +926,15 @@ efipart_realstrategy(void *devdata, int rw, daddr_t blk, size_t size,
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/* make sure we don't read past disk end */
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if ((off + size) / blkio->Media->BlockSize > d_offset + disk_blocks) {
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size = d_offset + disk_blocks - off / blkio->Media->BlockSize;
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diskend = d_offset + disk_blocks;
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readstart = off / blkio->Media->BlockSize;
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if (diskend <= readstart) {
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*rsize = 0;
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return (EIO);
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}
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size = diskend - readstart;
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size = size * blkio->Media->BlockSize;
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}
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