From: Namjae Jeon <linkinjeon@kernel.org>
To: Tristan Madani <tristmd@gmail.com>
Cc: Steve French <smfrench@gmail.com>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Tom Talpey <tom@talpey.com>,
linux-cifs@vger.kernel.org, stable@vger.kernel.org,
Tristan Madani <tristan@talencesecurity.com>
Subject: Re: [PATCH v2] ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment
Date: Sat, 18 Apr 2026 15:27:11 +0900 [thread overview]
Message-ID: <CAKYAXd-v03Tq_qjnDz-e3N8_S+rwxxnp5nucTriQ0DQLXHbRtg@mail.gmail.com> (raw)
In-Reply-To: <20260417193317.315698-1-tristan@talencesecurity.com>
On Sat, Apr 18, 2026 at 4:33 AM Tristan Madani <tristmd@gmail.com> wrote:
>
> smb2_get_ea() applies 4-byte alignment padding via memset() after
> writing each EA entry. The bounds check on buf_free_len is performed
> before the value memcpy, but the alignment memset fires unconditionally
> afterward with no check on remaining space.
>
> When the EA value exactly fills the remaining buffer (buf_free_len == 0
> after value subtraction), the alignment memset writes 1-3 NUL bytes
> past the buf_free_len boundary. In compound requests where the response
> buffer is shared across commands, the first command (e.g., READ) can
> consume most of the buffer, leaving a tight remainder for the QUERY_INFO
> EA response. The alignment memset then overwrites past the physical
> kvmalloc allocation into adjacent kernel heap memory.
>
> Add a bounds check before the alignment memset to ensure buf_free_len
> can accommodate the padding bytes.
>
> This is the same bug pattern fixed by commit beef2634f81f ("ksmbd: fix
> potencial OOB in get_file_all_info() for compound requests") and
> commit fda9522ed6af ("ksmbd: fix OOB write in QUERY_INFO for compound
> requests"), both of which added bounds checks before unconditional
> writes in QUERY_INFO response handlers.
>
> Cc: stable@vger.kernel.org
> Fixes: e2b76ab8b5c9 ("ksmbd: add support for read compound")
> Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
Applied it to #ksmbd-for-next-next.
Thanks!
prev parent reply other threads:[~2026-04-18 6:27 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-17 19:20 [PATCH] ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment Tristan Madani
2026-04-17 19:33 ` [PATCH v2] " Tristan Madani
2026-04-18 6:27 ` Namjae Jeon [this message]
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