Re: [PATCH bpf v2 1/7] bpf, sockmap: reject overflowing copy + len in bpf_msg_push_data()

[Jiayuan Chen]

On 6/12/26 12:53 AM, Alexei Starovoitov wrote:
> On Thu Jun 11, 2026 at 5:34 AM PDT, Jiayuan Chen wrote:
> > From: Weiming Shi <bestswngs@xxxxxxxxx>
> >
> > When the scatterlist ring is full or nearly full, bpf_msg_push_data()
> > enters a copy fallback path and computes copy + len for the page
> > allocation size. Since len comes from BPF with arg3_type = ARG_ANYTHING
> > and both are u32, a crafted len can wrap the sum to a small value,
> > causing an undersized allocation followed by an out-of-bounds memcpy.
> >
> >   BUG: unable to handle page fault for address: ffffed104089a402
> >   Oops: Oops: 0000 [#1] SMP KASAN NOPTI
> >   Call Trace:
> >    __asan_memcpy (mm/kasan/shadow.c:105)
> >    bpf_msg_push_data (net/core/filter.c:2852 net/core/filter.c:2788)
> >    bpf_prog_9ed8b5711920a7d7+0x2e/0x36
> >    sk_psock_msg_verdict (net/core/skmsg.c:934)
> >    tcp_bpf_sendmsg (net/ipv4/tcp_bpf.c:421 net/ipv4/tcp_bpf.c:584)
> >    __sys_sendto (net/socket.c:2206)
> >    do_syscall_64 (arch/x86/entry/syscall_64.c:94)
> >    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
> >
> > Add an overflow check before the allocation.
> >
> > Link: https://lore.kernel.org/all/20260424155913.A19FDC19425@xxxxxxxxxxxxxxx
> > Fixes: 6fff607e2f14 ("bpf: sk_msg program helper bpf_msg_push_data")
> > Tested-by: Xiang Mei <xmei5@xxxxxxx>
> > Tested-by: Xinyu Ma <mmmxny@xxxxxxxxx>
> > Reviewed-by: Jiayuan Chen <jiayuan.chen@xxxxxxxxx>
> > Cc: Jiayuan Chen <jiayuan.chen@xxxxxxxxx>
> > Signed-off-by: Weiming Shi <bestswngs@xxxxxxxxx>
> That's not the right way to post somebody else patches.
> You need to keep their authorship and SOB (as you did),
> but you also need to add your SOB after theirs.
>
> also pls target bpf-next.


Thanks Alexei, and sorry for the noise -- I'm still new to handling other
people's patches.

I'll keep their authorship and SOB and add my own SOB and retarget to 
bpf-next.