2021-10-13 20:33:16

by Marcelo Ricardo Leitner

Subject: [PATCH net] sctp: account stream padding length for reconf chunk

From: Eiichi Tsukata <[email protected]>

sctp_make_strreset_req() makes repeated calls to sctp_addto_chunk()
which will automatically account for padding on each call. inreq and
outreq are already 4 bytes aligned, but the payload is not and doing
SCTP_PAD4(a + b) (which _sctp_make_chunk() did implicitly here) is
different from SCTP_PAD4(a) + SCTP_PAD4(b) and not enough. It led to
possible attempt to use more buffer than it was allocated and triggered
a BUG_ON.

Cc: Vlad Yasevich <[email protected]>
Cc: Neil Horman <[email protected]>
Cc: Marcelo Ricardo Leitner <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Greg KH <[email protected]>
Fixes: cc16f00f6529 ("sctp: add support for generating stream reconf ssn reset request chunk")
Reported-by: Eiichi Tsukata <[email protected]>
Signed-off-by: Eiichi Tsukata <[email protected]>
Signed-off-by: Marcelo Ricardo Leitner <[email protected]>
Signed-off-by: Marcelo Ricardo Leitner <[email protected]>
---
net/sctp/sm_make_chunk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index b8fa8f1a7277..c7503fd64915 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -3697,7 +3697,7 @@ struct sctp_chunk *sctp_make_strreset_req(
outlen = (sizeof(outreq) + stream_len) * out;
inlen = (sizeof(inreq) + stream_len) * in;

- retval = sctp_make_reconf(asoc, outlen + inlen);
+ retval = sctp_make_reconf(asoc, SCTP_PAD4(outlen) + SCTP_PAD4(inlen));
if (!retval)
return NULL;

--
2.31.1

2021-10-14 04:47:21

by Xin Long

Subject: Re: [PATCH net] sctp: account stream padding length for reconf chunk

On Thu, Oct 14, 2021 at 4:27 AM Marcelo Ricardo Leitner
<[email protected]> wrote:
>
> From: Eiichi Tsukata <[email protected]>
>
> sctp_make_strreset_req() makes repeated calls to sctp_addto_chunk()
> which will automatically account for padding on each call. inreq and
> outreq are already 4 bytes aligned, but the payload is not and doing
> SCTP_PAD4(a + b) (which _sctp_make_chunk() did implicitly here) is
> different from SCTP_PAD4(a) + SCTP_PAD4(b) and not enough. It led to
> possible attempt to use more buffer than it was allocated and triggered
> a BUG_ON.
>
> Cc: Vlad Yasevich <[email protected]>
> Cc: Neil Horman <[email protected]>
> Cc: Marcelo Ricardo Leitner <[email protected]>
> Cc: "David S. Miller" <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: Greg KH <[email protected]>
> Fixes: cc16f00f6529 ("sctp: add support for generating stream reconf ssn reset request chunk")
> Reported-by: Eiichi Tsukata <[email protected]>
> Signed-off-by: Eiichi Tsukata <[email protected]>
> Signed-off-by: Marcelo Ricardo Leitner <[email protected]>
> Signed-off-by: Marcelo Ricardo Leitner <[email protected]>
> ---
> net/sctp/sm_make_chunk.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
> index b8fa8f1a7277..c7503fd64915 100644
> --- a/net/sctp/sm_make_chunk.c
> +++ b/net/sctp/sm_make_chunk.c
> @@ -3697,7 +3697,7 @@ struct sctp_chunk *sctp_make_strreset_req(
> outlen = (sizeof(outreq) + stream_len) * out;
> inlen = (sizeof(inreq) + stream_len) * in;
>
> - retval = sctp_make_reconf(asoc, outlen + inlen);
> + retval = sctp_make_reconf(asoc, SCTP_PAD4(outlen) + SCTP_PAD4(inlen));
> if (!retval)
> return NULL;
>
> --
> 2.31.1
>
Reviewed-by: Xin Long <[email protected]>

2021-10-14 15:44:05

by patchwork-bot+netdevbpf

Subject: Re: [PATCH net] sctp: account stream padding length for reconf chunk

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <[email protected]>:

On Wed, 13 Oct 2021 17:27:29 -0300 you wrote:
> From: Eiichi Tsukata <[email protected]>
>
> sctp_make_strreset_req() makes repeated calls to sctp_addto_chunk()
> which will automatically account for padding on each call. inreq and
> outreq are already 4 bytes aligned, but the payload is not and doing
> SCTP_PAD4(a + b) (which _sctp_make_chunk() did implicitly here) is
> different from SCTP_PAD4(a) + SCTP_PAD4(b) and not enough. It led to
> possible attempt to use more buffer than it was allocated and triggered
> a BUG_ON.
>
> [...]

Here is the summary with links:
- [net] sctp: account stream padding length for reconf chunk
https://git.kernel.org/netdev/net/c/a2d859e3fc97

You are awesome, thank you!
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