This is a note to let you know that I've just added the patch titled
bpf, test_run: Fix use-after-free issue in eth_skb_pkt_type()
to the 6.12-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:
bpf-test_run-fix-use-after-free-issue-in-eth_skb_pkt.patch
and it can be found in the queue-6.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 742bf1cd42def90f15753acc376592d1da336077
Author: Shigeru Yoshida <syoshida@xxxxxxxxxx>
Date: Wed Jan 22 00:06:42 2025 +0900
bpf, test_run: Fix use-after-free issue in eth_skb_pkt_type()
[ Upstream commit 6b3d638ca897e099fa99bd6d02189d3176f80a47 ]
KMSAN reported a use-after-free issue in eth_skb_pkt_type()[1]. The
cause of the issue was that eth_skb_pkt_type() accessed skb's data
that didn't contain an Ethernet header. This occurs when
bpf_prog_test_run_xdp() passes an invalid value as the user_data
argument to bpf_test_init().
Fix this by returning an error when user_data is less than ETH_HLEN in
bpf_test_init(). Additionally, remove the check for "if (user_size >
size)" as it is unnecessary.
[1]
BUG: KMSAN: use-after-free in eth_skb_pkt_type include/linux/etherdevice.h:627 [inline]
BUG: KMSAN: use-after-free in eth_type_trans+0x4ee/0x980 net/ethernet/eth.c:165
eth_skb_pkt_type include/linux/etherdevice.h:627 [inline]
eth_type_trans+0x4ee/0x980 net/ethernet/eth.c:165
__xdp_build_skb_from_frame+0x5a8/0xa50 net/core/xdp.c:635
xdp_recv_frames net/bpf/test_run.c:272 [inline]
xdp_test_run_batch net/bpf/test_run.c:361 [inline]
bpf_test_run_xdp_live+0x2954/0x3330 net/bpf/test_run.c:390
bpf_prog_test_run_xdp+0x148e/0x1b10 net/bpf/test_run.c:1318
bpf_prog_test_run+0x5b7/0xa30 kernel/bpf/syscall.c:4371
__sys_bpf+0x6a6/0xe20 kernel/bpf/syscall.c:5777
__do_sys_bpf kernel/bpf/syscall.c:5866 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5864 [inline]
__x64_sys_bpf+0xa4/0xf0 kernel/bpf/syscall.c:5864
x64_sys_call+0x2ea0/0x3d90 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd9/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was created at:
free_pages_prepare mm/page_alloc.c:1056 [inline]
free_unref_page+0x156/0x1320 mm/page_alloc.c:2657
__free_pages+0xa3/0x1b0 mm/page_alloc.c:4838
bpf_ringbuf_free kernel/bpf/ringbuf.c:226 [inline]
ringbuf_map_free+0xff/0x1e0 kernel/bpf/ringbuf.c:235
bpf_map_free kernel/bpf/syscall.c:838 [inline]
bpf_map_free_deferred+0x17c/0x310 kernel/bpf/syscall.c:862
process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0xa2b/0x1b60 kernel/workqueue.c:3310
worker_thread+0xedf/0x1550 kernel/workqueue.c:3391
kthread+0x535/0x6b0 kernel/kthread.c:389
ret_from_fork+0x6e/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
CPU: 1 UID: 0 PID: 17276 Comm: syz.1.16450 Not tainted 6.12.0-05490-g9bb88c659673 #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
Fixes: be3d72a2896c ("bpf: move user_size out of bpf_test_init")
Reported-by: syzkaller <syzkaller@xxxxxxxxxxxxxxxx>
Suggested-by: Martin KaFai Lau <martin.lau@xxxxxxxxx>
Signed-off-by: Shigeru Yoshida <syoshida@xxxxxxxxxx>
Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxxx>
Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20250121150643.671650-1-syoshida@xxxxxxxxxx
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 501ec4249fedc..8612023bec60d 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -660,12 +660,9 @@ static void *bpf_test_init(const union bpf_attr *kattr, u32 user_size,
void __user *data_in = u64_to_user_ptr(kattr->test.data_in);
void *data;
- if (size < ETH_HLEN || size > PAGE_SIZE - headroom - tailroom)
+ if (user_size < ETH_HLEN || user_size > PAGE_SIZE - headroom - tailroom)
return ERR_PTR(-EINVAL);
- if (user_size > size)
- return ERR_PTR(-EMSGSIZE);
-
size = SKB_DATA_ALIGN(size);
data = kzalloc(size + headroom + tailroom, GFP_USER);
if (!data)
