Re: [PATCH] packfile: Correct zlib buffer handling

[Eric Sunshine <sunshine@sunshineco.com>]

On Fri, May 25, 2018 at 7:17 PM, Jeremy Linton <lintonrjeremy@gmail.com> wrote:
> The buffer being passed to zlib includes a null terminator that
> git needs to keep in place. unpack_compressed_entry() attempts to
> detect the case that the source buffer hasn't been fully consumed
> by checking to see if the destination buffer has been over consumed.
>
> This yields two problems, first a single byte overrun won't be detected
> properly because the Z_STREAM_END will then be set, but the null
> terminator will have been overwritten. The other problem is that
> more recent zlib patches have been poisoning the unconsumed portions
> of the buffers which also overwrites the null, while correctly
> returning length and status.
>
> Lets rely on the fact that the source buffer will only be fully

s/Lets/Let's/

> consumed when the when the destination buffer is inflated to the

s/when the when the/when the/

> correct size. We can do this by passing zlib the correct buffer size
> and properly checking the return status. The latter check actually
> already exists if the buffer size is correct.
>
> Signed-off-by: Jeremy Linton <lintonrjeremy@gmail.com>