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Message-ID: <885129e4-d6d6-57d3-21d3-a83bd98c3994@suse.com>
Date: Sun, 5 Jul 2020 17:48:17 +0300
From: Nikolay Borisov <nborisov@...e.com>
To: trix@...hat.com, clm@...com, josef@...icpanda.com, dsterba@...e.com
Cc: linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] btfrs: initialize return of btrfs_extent_same
On 5.07.20 г. 17:20 ч., trix@...hat.com wrote:
> From: Tom Rix <trix@...hat.com>
>
> clang static analysis flags a garbage return
>
> fs/btrfs/reflink.c:611:2: warning: Undefined or garbage value returned to caller [core.uninitialized.UndefReturn]
> return ret;
> ^~~~~~~~~~
> ret will not be set when olen is 0
> When olen is 0, this function does no work.
>
> So initialize ret to 0
>
> Signed-off-by: Tom Rix <trix@...hat.com>
Patch itself is good however, the bug cannot currently be triggered, due
to the following code in the sole caller (btrfs_remap_file_range):
15 if (ret < 0 || len == 0)
14 goto out_unlock;
13
12 if (remap_flags & REMAP_FILE_DEDUP)
11 ret = btrfs_extent_same(src_inode, off, len,
dst_inode, destoff);
10 else
9 ret = btrfs_clone_files(dst_file, src_file, off,
len, destoff);
i.e len is guaranteed to be non-zero
> ---
> fs/btrfs/reflink.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/reflink.c b/fs/btrfs/reflink.c
> index 040009d1cc31..200a80fcbecb 100644
> --- a/fs/btrfs/reflink.c
> +++ b/fs/btrfs/reflink.c
> @@ -572,7 +572,7 @@ static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 len,
> static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
> struct inode *dst, u64 dst_loff)
> {
> - int ret;
> + int ret = 0;
> u64 i, tail_len, chunk_count;
> struct btrfs_root *root_dst = BTRFS_I(dst)->root;
>
>
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