Re: [PATCH] btrfs: send: fix buffer overflow detection when copying path to cache entry

[Wang Yugui <wangyugui@e16-tech.com>]

Hi,

> Hi,
> 
> > From: Filipe Manana <fdmanana@suse.com>
> > 
> > Starting with commit c0247d289e73 ("btrfs: send: annotate struct
> > name_cache_entry with __counted_by()") we annotated the variable length
> > array "name" from the name_cache_entry structure with __counted_by() to
> > improve overflow detection. However that alone was not correct, because
> > the length of that array does not match the "name_len" field - it matches
> > that plus 1 to include the nul string terminador, so that makes a
> > fortified kernel think there's an overflow and report a splat like this:
> 
> xfstests generic/591 failed with this patch.
> 
> generic/591 1s ... - output mismatch (see
> /usr/hpc-bio/xfstests/results//generic/591.out.bad)
>     --- tests/generic/591.out   2024-08-06 21:26:52.100477701 +0800
>     +++ /usr/hpc-bio/xfstests/results//generic/591.out.bad      2024-09-22 06:00:37.920543850 +0800
>     @@ -1,5 +1,10 @@
>      QA output created by 591
>      concurrent reader with O_DIRECT
>     +splice-test: open: /mnt/test/a: Is a directory
>      concurrent reader without O_DIRECT
>     +splice-test: open: /mnt/test/a: Is a directory
>      sequential reader with O_DIRECT
>     +splice-test: open: /mnt/test/a: Is a directory
>     ...
>     (Run 'diff -u /usr/hpc-bio/xfstests/tests/generic/591.out /usr/hpc-bio/xfstests/results//generic/591.out.bad'  to see the entire diff)

This is just a noise. Sorry.

‘splice-test: open: /mnt/test/a: Is a directory’ is a problem of other patch,
not this one.

Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2024/09/22



> Best Regards
> Wang Yugui (wangyugui@e16-tech.com)
> 2024/09/22
> 
>