Re: [PATCH 2/2] linux-user/gen-vdso: Don't write off the end of buf[]

[Peter Maydell <peter.maydell@linaro.org>]

On Thu, 10 Jul 2025 at 18:07, Peter Maydell <peter.maydell@linaro.org> wrote:
>
> In gen-vdso we load in a file and assume it's a valid ELF file.  In
> particular we assume it's big enough to be able to read the ELF
> information in e_ident in the ELF header.
>
> Add a check that the total file length is at least big enough for all
> the e_ident bytes, which is good enough for the code in gen-vdso.c.
> This will catch the most obvious possible bad input file (truncated)
> and allow us to run the sanity checks like "not actually an ELF file"
> without potentially crashing.
>
> The code in elf32_process() and elf64_process() still makes
> assumptions about the file being well-formed, but this is OK because
> we only run it on the vdso binaries that we create ourselves in the
> build process by running the compiler.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> Hardening all of elf*_process() seems like overkill, but this is
> an easy check to add.

Subject line should say "read off the end", of course.

-- PMM