kernel/linux.git/net/bpf, branch v6.18.21

bpf: Fix reference count leak in bpf_prog_test_run_xdp()

2026-01-17T15:35:31+00:00

[ Upstream commit ec69daabe45256f98ac86c651b8ad1b2574489a7 ] syzbot is reporting unregister_netdevice: waiting for sit0 to become free. Usage count = 2 problem. A debug printk() patch found that a refcount is obtained at xdp_convert_md_to_buff() from bpf_prog_test_run_xdp(). According to commit ec94670fcb3b ("bpf: Support specifying ingress via xdp_md context in BPF_PROG_TEST_RUN"), the refcount obtained by xdp_convert_md_to_buff() will be released by xdp_convert_buff_to_md(). Therefore, we can consider that the error handling path introduced by commit 1c1949982524 ("bpf: introduce frags support to bpf_prog_test_run_xdp()") forgot to call xdp_convert_buff_to_md(). Reported-by: syzbot+881d65229ca4f9ae8c84@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=881d65229ca4f9ae8c84 Fixes: 1c1949982524 ("bpf: introduce frags support to bpf_prog_test_run_xdp()") Signed-off-by: Tetsuo Handa Reviewed-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/af090e53-9d9b-4412-8acb-957733b3975c@I-love.SAKURA.ne.jp Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

bpf, test_run: Subtract size of xdp_frame from allowed metadata size

2026-01-17T15:35:31+00:00

[ Upstream commit e558cca217790286e799a8baacd1610bda31b261 ] The xdp_frame structure takes up part of the XDP frame headroom, limiting the size of the metadata. However, in bpf_test_run, we don't take this into account, which makes it possible for userspace to supply a metadata size that is too large (taking up the entire headroom). If userspace supplies such a large metadata size in live packet mode, the xdp_update_frame_from_buff() call in xdp_test_run_init_page() call will fail, after which packet transmission proceeds with an uninitialised frame structure, leading to the usual Bad Stuff. The commit in the Fixes tag fixed a related bug where the second check in xdp_update_frame_from_buff() could fail, but did not add any additional constraints on the metadata size. Complete the fix by adding an additional check on the metadata size. Reorder the checks slightly to make the logic clearer and add a comment. Link: https://lore.kernel.org/r/fa2be179-bad7-4ee3-8668-4903d1853461@hust.edu.cn Fixes: b6f1f780b393 ("bpf, test_run: Fix packet size check for live packet mode") Reported-by: Yinhao Hu Reported-by: Kaiyan Mei Signed-off-by: Toke Høiland-Jørgensen Reviewed-by: Amery Hung Link: https://lore.kernel.org/r/20260105114747.1358750-1-toke@redhat.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

bpf: Do not let BPF test infra emit invalid GSO types to stack

2025-12-18T13:02:33+00:00

[ Upstream commit 04a899573fb87273a656f178b5f920c505f68875 ] Yinhao et al. reported that their fuzzer tool was able to trigger a skb_warn_bad_offload() from netif_skb_features() -> gso_features_check(). When a BPF program - triggered via BPF test infra - pushes the packet to the loopback device via bpf_clone_redirect() then mentioned offload warning can be seen. GSO-related features are then rightfully disabled. We get into this situation due to convert___skb_to_skb() setting gso_segs and gso_size but not gso_type. Technically, it makes sense that this warning triggers since the GSO properties are malformed due to the gso_type. Potentially, the gso_type could be marked non-trustworthy through setting it at least to SKB_GSO_DODGY without any other specific assumptions, but that also feels wrong given we should not go further into the GSO engine in the first place. The checks were added in 121d57af308d ("gso: validate gso_type in GSO handlers") because there were malicious (syzbot) senders that combine a protocol with a non-matching gso_type. If we would want to drop such packets, gso_features_check() currently only returns feature flags via netif_skb_features(), so one location for potentially dropping such skbs could be validate_xmit_unreadable_skb(), but then otoh it would be an additional check in the fast-path for a very corner case. Given bpf_clone_redirect() is the only place where BPF test infra could emit such packets, lets reject them right there. Fixes: 850a88cc4096 ("bpf: Expose __sk_buff wire_len/gso_segs to BPF_PROG_TEST_RUN") Fixes: cf62089b0edd ("bpf: Add gso_size to __sk_buff") Reported-by: Yinhao Hu Reported-by: Kaiyan Mei Reported-by: Dongliang Mu Signed-off-by: Daniel Borkmann Signed-off-by: Martin KaFai Lau Link: https://patch.msgid.link/20251020075441.127980-1-daniel@iogearbox.net Signed-off-by: Sasha Levin

bpf: Do not disable preemption in bpf_test_run().

2025-10-17T18:29:35+00:00

The timer mode is initialized to NO_PREEMPT mode by default, this disables preemption and force execution in atomic context causing issue on PREEMPT_RT configurations when invoking spin_lock_bh(), leading to the following warning: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 6107, name: syz.0.17 preempt_count: 1, expected: 0 RCU nest depth: 1, expected: 1 Preemption disabled at: [] bpf_test_timer_enter+0xf8/0x140 net/bpf/test_run.c:42 Fix this, by removing NO_PREEMPT/NO_MIGRATE mode check. Also, the test timer context no longer needs explicit calls to migrate_disable()/migrate_enable() with rcu_read_lock()/rcu_read_unlock(). Use helpers rcu_read_lock_dont_migrate() and rcu_read_unlock_migrate() instead. Reported-by: syzbot+1f1fbecb9413cdbfbef8@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1f1fbecb9413cdbfbef8 Suggested-by: Yonghong Song Suggested-by: Menglong Dong Acked-by: Yonghong Song Tested-by: syzbot+1f1fbecb9413cdbfbef8@syzkaller.appspotmail.com Co-developed-by: Brahmajit Das Signed-off-by: Brahmajit Das Signed-off-by: Sahil Chandna Link: https://lore.kernel.org/r/20251014185635.10300-1-chandna.sahil@gmail.com Signed-off-by: Alexei Starovoitov

bpf: test_run: Fix ctx leak in bpf_prog_test_run_xdp error path

2025-10-14T19:07:30+00:00

Fix a memory leak in bpf_prog_test_run_xdp() where the context buffer allocated by bpf_ctx_init() is not freed when the function returns early due to a data size check. On the failing path: ctx = bpf_ctx_init(...); if (kattr->test.data_size_in - meta_sz < ETH_HLEN) return -EINVAL; The early return bypasses the cleanup label that kfree()s ctx, leading to a leak detectable by kmemleak under fuzzing. Change the return to jump to the existing free_ctx label. Fixes: fe9544ed1a2e ("bpf: Support specifying linear xdp packet data size for BPF_PROG_TEST_RUN") Reported-by: BPF Runtime Fuzzer (BRF) Signed-off-by: Shardul Bankar Signed-off-by: Martin KaFai Lau Acked-by: Jiri Olsa Acked-by: Daniel Borkmann Link: https://patch.msgid.link/20251014120037.1981316-1-shardulsb08@gmail.com

Merge branch 'bpf-next/xdp_pull_data' into 'bpf-next/master'

2025-09-23T23:23:58+00:00

Merge the xdp_pull_data stable branch into the master branch. No conflict. Signed-off-by: Martin KaFai Lau

bpf: Support specifying linear xdp packet data size for BPF_PROG_TEST_RUN

2025-09-23T20:35:12+00:00

To test bpf_xdp_pull_data(), an xdp packet containing fragments as well as free linear data area after xdp->data_end needs to be created. However, bpf_prog_test_run_xdp() always fills the linear area with data_in before creating fragments, leaving no space to pull data. This patch will allow users to specify the linear data size through ctx->data_end. Currently, ctx_in->data_end must match data_size_in and will not be the final ctx->data_end seen by xdp programs. This is because ctx->data_end is populated according to the xdp_buff passed to test_run. The linear data area available in an xdp_buff, max_linear_sz, is alawys filled up before copying data_in into fragments. This patch will allow users to specify the size of data that goes into the linear area. When ctx_in->data_end is different from data_size_in, only ctx_in->data_end bytes of data will be put into the linear area when creating the xdp_buff. While ctx_in->data_end will be allowed to be different from data_size_in, it cannot be larger than the data_size_in as there will be no data to copy from user space. If it is larger than the maximum linear data area size, the layout suggested by the user will not be honored. Data beyond max_linear_sz bytes will still be copied into fragments. Finally, since it is possible for a NIC to produce a xdp_buff with empty linear data area, allow it when calling bpf_test_init() from bpf_prog_test_run_xdp() so that we can test XDP kfuncs with such xdp_buff. This is done by moving lower-bound check to callers as most of them already do except bpf_prog_test_run_skb(). The change also fixes a bug that allows passing an xdp_buff with data < ETH_HLEN. This can happen when ctx is used and metadata is at least ETH_HLEN. Signed-off-by: Amery Hung Signed-off-by: Martin KaFai Lau Link: https://patch.msgid.link/20250922233356.3356453-7-ameryhung@gmail.com

bpf: Make variables in bpf_prog_test_run_xdp less confusing

2025-09-23T20:35:12+00:00

Change the variable naming in bpf_prog_test_run_xdp() to make the overall logic less confusing. As different modes were added to the function over the time, some variables got overloaded, making it hard to understand and changing the code becomes error-prone. Replace "size" with "linear_sz" where it refers to the size of metadata and data. If "size" refers to input data size, use test.data_size_in directly. Replace "max_data_sz" with "max_linear_sz" to better reflect the fact that it is the maximum size of metadata and data (i.e., linear_sz). Also, xdp_rxq.frags_size is always PAGE_SIZE, so just set it directly instead of subtracting headroom and tailroom and adding them back. Signed-off-by: Amery Hung Signed-off-by: Martin KaFai Lau Link: https://patch.msgid.link/20250922233356.3356453-6-ameryhung@gmail.com

bpf: Standardize function declaration style

2025-08-08T02:18:03+00:00

'noinlne' after 'int' cause "ERROR: inline keyword should sit between storage class and type" by checkpatch.pl - Standardize function declaration style by moving 'noinline' modifier - Fix asm volatile statement formatting Signed-off-by: Li Jun Link: https://lore.kernel.org/r/20250730105019.436235-1-lijun01@kylinos.cn Signed-off-by: Alexei Starovoitov

bpf: Add attach_type field to bpf_link

2025-07-11T17:51:55+00:00

Attach_type will be set when a link is created by user. It is better to record attach_type in bpf_link generically and have it available universally for all link types. So add the attach_type field in bpf_link and move the sleepable field to avoid unnecessary gap padding. Signed-off-by: Tao Chen Signed-off-by: Andrii Nakryiko Acked-by: Daniel Borkmann Acked-by: Jiri Olsa Link: https://lore.kernel.org/bpf/20250710032038.888700-2-chen.dylane@linux.dev