From: Mark Wielaard <mark@klomp.org>
To: vvvvvv@google.com, elfutils-devel@sourceware.org
Cc: kernel-team@android.com, maennich@google.com
Subject: Re: [PATCH] libdw: check offset dwarf_formstring in all cases
Date: Fri, 17 Nov 2023 16:31:23 +0100 [thread overview]
Message-ID: <525de8c7fda5b1ebb41085c11d585f738f952e24.camel@klomp.org> (raw)
In-Reply-To: <20231116212922.4148717-1-vvvvvv@google.com>
Hi Aleksei,
On Thu, 2023-11-16 at 21:29 +0000, vvvvvv@google.com wrote:
> This check was initially added to test if offset overflows the safe
> prefix where any string will be null-terminated. However the check
> was placed in a wrong place and didn't cover all `attrp->form` cases.
>
> * libdw/dwarf_formstring.c (dwarf_formstring): Move offset check
> right before returning the result.
Oops. I see how this happened for DW_FORM_strp and DW_FORM_line_strp we
use __libdw_read_offset which already check the section offset. But of
course those use d_size, not the string_section_size that was setup in
elf_begin_elf. So the check is also needed for them.
> Signed-off-by: Aleksei Vetrov <vvvvvv@google.com>
> ---
> libdw/dwarf_formstring.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/libdw/dwarf_formstring.c b/libdw/dwarf_formstring.c
> index 0ee42411..65f03a5e 100644
> --- a/libdw/dwarf_formstring.c
> +++ b/libdw/dwarf_formstring.c
> @@ -173,11 +173,11 @@ dwarf_formstring (Dwarf_Attribute *attrp)
> off = read_4ubyte_unaligned (dbg, datap);
> else
> off = read_8ubyte_unaligned (dbg, datap);
> -
> - if (off >= data_size)
> - goto invalid_offset;
> }
>
> + if (off >= data_size)
> + goto invalid_offset;
> +
> return (const char *) data->d_buf + off;
> }
> INTDEF(dwarf_formstring)
Applied.
Thanks,
Mark
prev parent reply other threads:[~2023-11-17 15:31 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-16 21:29 vvvvvv
2023-11-17 15:31 ` Mark Wielaard [this message]
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