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You-Kai Zheng
646c14273d
[ Upstream commitb95181f392] The variable-sized buffer buf in struct btrfs_ioctl_search_args_v2 is declared as __u64[], but it holds a packed byte stream of search results, where all offsets into the buffer are in bytes. Declaring buf as __u64[] makes it easy for user space to write incorrect pointer arithmetic: adding a byte offset directly to a __u64 pointer scales the offset by 8, landing at byte position offset*8 instead of offset. This recently caused an infinite loop in btrfs-progs: the accessor read all-zero data from misaddressed items, which fed zeroed search keys back into the ioctl loop and spun forever. The issue was worked around at the time by disabling TREE_SEARCH_V2 entirely in btrfs-progs (d73e69824854: "btrfs-progs: temporarily disable usage of v2 of search tree ioctl"). The kernel side already treats buf as a byte buffer, so change the declaration to __u8[] to match the actual semantics and prevent similar misuse in user space. The change is ABI compatible: both the structure size and alignment are unchanged. Fixes:cc68a8a5a4("btrfs: new ioctl TREE_SEARCH_V2") Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: You-Kai Zheng <ykzheng@synology.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Sasha Levin <sashal@kernel.org>