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FWei-HWJaegeuk Kim
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Jaegeuk Kim
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f2fs: fix a dead loop in f2fs_fiemap()
A dead loop can be triggered in f2fs_fiemap() using the test case as below: ... fd = open(); fallocate(fd, 0, 0, 4294967296); ioctl(fd, FS_IOC_FIEMAP, fiemap_buf); ... It's caused by an overflow in __get_data_block(): ... bh->b_size = map.m_len << inode->i_blkbits; ... map.m_len is an unsigned int, and bh->b_size is a size_t which is 64 bits on 64 bits archtecture, type conversion from an unsigned int to a size_t will result in an overflow. In the above-mentioned case, bh->b_size will be zero, and f2fs_fiemap() will call get_data_block() at block 0 again an again. Fix this by adding a force conversion before left shift. Signed-off-by: Wei Fang <fangwei1@huawei.com> Acked-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Diff for: fs/f2fs/data.c

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Original file line numberDiff line numberDiff line change
@@ -964,7 +964,7 @@ static int __get_data_block(struct inode *inode, sector_t iblock,
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if (!err) {
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map_bh(bh, inode->i_sb, map.m_pblk);
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bh->b_state = (bh->b_state & ~F2FS_MAP_FLAGS) | map.m_flags;
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bh->b_size = map.m_len << inode->i_blkbits;
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bh->b_size = (u64)map.m_len << inode->i_blkbits;
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}
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return err;
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}

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