This is a note to let you know that I've just added the patch titled
net: core: remove unnecessary frame_sz check in bpf_xdp_adjust_tail()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-core-remove-unnecessary-frame_sz-check-in-bpf_xdp_adjust_tail.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d14eea09edf427fa36bd446f4a3271f99164202f Mon Sep 17 00:00:00 2001
From: Andrew Kanner <andrew.kanner@xxxxxxxxx>
Date: Thu, 3 Aug 2023 21:03:18 +0200
Subject: net: core: remove unnecessary frame_sz check in bpf_xdp_adjust_tail()
From: Andrew Kanner <andrew.kanner@xxxxxxxxx>
commit d14eea09edf427fa36bd446f4a3271f99164202f upstream.
Syzkaller reported the following issue:
=======================================
Too BIG xdp->frame_sz = 131072
WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121
____bpf_xdp_adjust_tail net/core/filter.c:4121 [inline]
WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121
bpf_xdp_adjust_tail+0x466/0xa10 net/core/filter.c:4103
...
Call Trace:
<TASK>
bpf_prog_4add87e5301a4105+0x1a/0x1c
__bpf_prog_run include/linux/filter.h:600 [inline]
bpf_prog_run_xdp include/linux/filter.h:775 [inline]
bpf_prog_run_generic_xdp+0x57e/0x11e0 net/core/dev.c:4721
netif_receive_generic_xdp net/core/dev.c:4807 [inline]
do_xdp_generic+0x35c/0x770 net/core/dev.c:4866
tun_get_user+0x2340/0x3ca0 drivers/net/tun.c:1919
tun_chr_write_iter+0xe8/0x210 drivers/net/tun.c:2043
call_write_iter include/linux/fs.h:1871 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x650/0xe40 fs/read_write.c:584
ksys_write+0x12f/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
xdp->frame_sz > PAGE_SIZE check was introduced in commit c8741e2bfe87
("xdp: Allow bpf_xdp_adjust_tail() to grow packet size"). But Jesper
Dangaard Brouer <jbrouer@xxxxxxxxxx> noted that after introducing the
xdp_init_buff() which all XDP driver use - it's safe to remove this
check. The original intend was to catch cases where XDP drivers have
not been updated to use xdp.frame_sz, but that is not longer a concern
(since xdp_init_buff).
Running the initial syzkaller repro it was discovered that the
contiguous physical memory allocation is used for both xdp paths in
tun_get_user(), e.g. tun_build_skb() and tun_alloc_skb(). It was also
stated by Jesper Dangaard Brouer <jbrouer@xxxxxxxxxx> that XDP can
work on higher order pages, as long as this is contiguous physical
memory (e.g. a page).
Reported-and-tested-by: syzbot+f817490f5bd20541b90a@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/all/000000000000774b9205f1d8a80d@xxxxxxxxxx/T/
Link: https://syzkaller.appspot.com/bug?extid=f817490f5bd20541b90a
Link: https://lore.kernel.org/all/20230725155403.796-1-andrew.kanner@xxxxxxxxx/T/
Fixes: 43b5169d8355 ("net, xdp: Introduce xdp_init_buff utility routine")
Signed-off-by: Andrew Kanner <andrew.kanner@xxxxxxxxx>
Acked-by: Jesper Dangaard Brouer <hawk@xxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230803190316.2380231-1-andrew.kanner@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/filter.c | 6 ------
1 file changed, 6 deletions(-)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3843,12 +3843,6 @@ BPF_CALL_2(bpf_xdp_adjust_tail, struct x
if (unlikely(data_end > data_hard_end))
return -EINVAL;
- /* ALL drivers MUST init xdp->frame_sz, chicken check below */
- if (unlikely(xdp->frame_sz > PAGE_SIZE)) {
- WARN_ONCE(1, "Too BIG xdp->frame_sz = %d\n", xdp->frame_sz);
- return -EINVAL;
- }
-
if (unlikely(data_end < xdp->data + ETH_HLEN))
return -EINVAL;
Patches currently in stable-queue which might be from andrew.kanner@xxxxxxxxx are
queue-5.15/net-core-remove-unnecessary-frame_sz-check-in-bpf_xdp_adjust_tail.patch
queue-5.15/drivers-net-prevent-tun_build_skb-to-exceed-the-packet-size-limit.patch
