linux.git/kernel/bpf/devmap.c, branch v7.2-rc1 Linux kernel source tree bpf: Run generic devmap egress prog on private skb 2026-06-13T01:21:01+00:00 Sun Jian sun.jian.kdev@gmail.com 2026-06-12T11:40:31+00:00 6001896f00984d317fb75160ba05c4a885fbe2a0 Generic XDP devmap multi redirect uses skb_clone() for intermediate destinations and sends the last destination with the original skb. This can leave multiple destinations sharing the same packet data. This becomes visible after generic devmap egress-program support was added: a devmap egress program may mutate packet data, and another destination sharing the same data can observe that mutation. Native XDP broadcast redirect does not have this issue because xdpf_clone() copies the frame data for each destination. Generic XDP should provide the same per-destination isolation before running a devmap egress program. Fix this by making cloned skbs private before running the generic devmap egress program. Use skb_copy() instead of skb_unshare() so allocation failure does not consume the skb and the existing caller error paths keep their ownership semantics. Fixes: 2ea5eabaf04a ("bpf: devmap: Implement devmap prog execution for generic XDP") Suggested-by: Jiayuan Chen <jiayuan.chen@linux.dev> Suggested-by: Jakub Kicinski <kuba@kernel.org> Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com> Link: https://lore.kernel.org/r/20260612114032.244616-2-sun.jian.kdev@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Generic XDP devmap multi redirect uses skb_clone() for intermediate
destinations and sends the last destination with the original skb. This
can leave multiple destinations sharing the same packet data.

This becomes visible after generic devmap egress-program support was
added: a devmap egress program may mutate packet data, and another
destination sharing the same data can observe that mutation.

Native XDP broadcast redirect does not have this issue because
xdpf_clone() copies the frame data for each destination. Generic XDP
should provide the same per-destination isolation before running a
devmap egress program.

Fix this by making cloned skbs private before running the generic devmap
egress program. Use skb_copy() instead of skb_unshare() so allocation
failure does not consume the skb and the existing caller error paths keep
their ownership semantics.

Fixes: 2ea5eabaf04a ("bpf: devmap: Implement devmap prog execution for generic XDP")
Suggested-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
Link: https://lore.kernel.org/r/20260612114032.244616-2-sun.jian.kdev@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Reject fragmented frames in devmap 2026-06-05T15:20:12+00:00 Zhao Zhang zzhan461@ucr.edu 2026-06-02T08:43:33+00:00 aa496720618f1a6054f1c870bf10b4f6c99bf656 Devmap broadcast redirects clone the packet for all but the last destination. For native XDP, that clone path copies only the linear xdp_frame data, while fragmented frames keep skb_shared_info in tailroom outside the linear area. Cloning such a frame leaves XDP_FLAGS_HAS_FRAGS set but without valid frag metadata, and the later free path can interpret uninitialized tail data as skb_shared_info, leading to an out-of-bounds access during frame return. Reject fragmented native XDP frames in dev_map_enqueue_clone(). Add the same restriction to the generic XDP clone path in dev_map_redirect_clone(). Generic XDP represents fragmented packets as nonlinear skbs, and rejecting them here keeps clone-based broadcast support aligned between native and generic XDP. Fixes: e624d4ed4aa8 ("xdp: Extend xdp_redirect_map with broadcast support") Cc: stable@kernel.org Reported-by: Yuan Tan <yuantan098@gmail.com> Reported-by: Zhengchuan Liang <zcliangcn@gmail.com> Reported-by: Xin Liu <bird@lzu.edu.cn> Assisted-by: Codex:GPT-5.4 Signed-off-by: Zhao Zhang <zzhan461@ucr.edu> Signed-off-by: Ren Wei <n05ec@lzu.edu.cn> Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/r/21c2d153dd25603d359069a02bf06779b51f6423.1780385378.git.zzhan461@ucr.edu Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Devmap broadcast redirects clone the packet for all but the last
destination.

For native XDP, that clone path copies only the linear xdp_frame data,
while fragmented frames keep skb_shared_info in tailroom outside the
linear area. Cloning such a frame leaves XDP_FLAGS_HAS_FRAGS set but
without valid frag metadata, and the later free path can interpret
uninitialized tail data as skb_shared_info, leading to an out-of-bounds
access during frame return.

Reject fragmented native XDP frames in dev_map_enqueue_clone().

Add the same restriction to the generic XDP clone path in
dev_map_redirect_clone(). Generic XDP represents fragmented packets as
nonlinear skbs, and rejecting them here keeps clone-based broadcast
support aligned between native and generic XDP.

Fixes: e624d4ed4aa8 ("xdp: Extend xdp_redirect_map with broadcast support")
Cc: stable@kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Zhengchuan Liang <zcliangcn@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Assisted-by: Codex:GPT-5.4
Signed-off-by: Zhao Zhang <zzhan461@ucr.edu>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/21c2d153dd25603d359069a02bf06779b51f6423.1780385378.git.zzhan461@ucr.edu
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Use RCU-safe iteration in dev_map_redirect_multi() SKB path 2026-03-24T22:17:20+00:00 David Carlier devnexen@gmail.com 2026-03-20T07:26:45+00:00 8ed82f807bb09d2c8455aaa665f2c6cb17bc6a19 The DEVMAP_HASH branch in dev_map_redirect_multi() uses hlist_for_each_entry_safe() to iterate hash buckets, but this function runs under RCU protection (called from xdp_do_generic_redirect_map() in softirq context). Concurrent writers (__dev_map_hash_update_elem, dev_map_hash_delete_elem) modify the list using RCU primitives (hlist_add_head_rcu, hlist_del_rcu). hlist_for_each_entry_safe() performs plain pointer dereferences without rcu_dereference(), missing the acquire barrier needed to pair with writers' rcu_assign_pointer(). On weakly-ordered architectures (ARM64, POWER), a reader can observe a partially-constructed node. It also defeats CONFIG_PROVE_RCU lockdep validation and KCSAN data-race detection. Replace with hlist_for_each_entry_rcu() using rcu_read_lock_bh_held() as the lockdep condition, consistent with the rcu_dereference_check() used in the DEVMAP (non-hash) branch of the same functions. Also fix the same incorrect lockdep_is_held(&dtab->index_lock) condition in dev_map_enqueue_multi(), where the lock is not held either. Fixes: e624d4ed4aa8 ("xdp: Extend xdp_redirect_map with broadcast support") Signed-off-by: David Carlier <devnexen@gmail.com> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Link: https://patch.msgid.link/20260320072645.16731-1-devnexen@gmail.com 
The DEVMAP_HASH branch in dev_map_redirect_multi() uses
hlist_for_each_entry_safe() to iterate hash buckets, but this function
runs under RCU protection (called from xdp_do_generic_redirect_map()
in softirq context). Concurrent writers (__dev_map_hash_update_elem,
dev_map_hash_delete_elem) modify the list using RCU primitives
(hlist_add_head_rcu, hlist_del_rcu).

hlist_for_each_entry_safe() performs plain pointer dereferences without
rcu_dereference(), missing the acquire barrier needed to pair with
writers' rcu_assign_pointer(). On weakly-ordered architectures (ARM64,
POWER), a reader can observe a partially-constructed node. It also
defeats CONFIG_PROVE_RCU lockdep validation and KCSAN data-race
detection.

Replace with hlist_for_each_entry_rcu() using rcu_read_lock_bh_held()
as the lockdep condition, consistent with the rcu_dereference_check()
used in the DEVMAP (non-hash) branch of the same functions. Also fix
the same incorrect lockdep_is_held(&dtab->index_lock) condition in
dev_map_enqueue_multi(), where the lock is not held either.

Fixes: e624d4ed4aa8 ("xdp: Extend xdp_redirect_map with broadcast support")
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20260320072645.16731-1-devnexen@gmail.com
bpf: Fix race in devmap on PREEMPT_RT 2026-02-28T00:08:10+00:00 Jiayuan Chen jiayuan.chen@shopee.com 2026-02-25T12:14:56+00:00 1872e75375c40add4a35990de3be77b5741c252c On PREEMPT_RT kernels, the per-CPU xdp_dev_bulk_queue (bq) can be accessed concurrently by multiple preemptible tasks on the same CPU. The original code assumes bq_enqueue() and __dev_flush() run atomically with respect to each other on the same CPU, relying on local_bh_disable() to prevent preemption. However, on PREEMPT_RT, local_bh_disable() only calls migrate_disable() (when PREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable preemption, which allows CFS scheduling to preempt a task during bq_xmit_all(), enabling another task on the same CPU to enter bq_enqueue() and operate on the same per-CPU bq concurrently. This leads to several races: 1. Double-free / use-after-free on bq->q[]: bq_xmit_all() snapshots cnt = bq->count, then iterates bq->q[0..cnt-1] to transmit frames. If preempted after the snapshot, a second task can call bq_enqueue() -> bq_xmit_all() on the same bq, transmitting (and freeing) the same frames. When the first task resumes, it operates on stale pointers in bq->q[], causing use-after-free. 2. bq->count and bq->q[] corruption: concurrent bq_enqueue() modifying bq->count and bq->q[] while bq_xmit_all() is reading them. 3. dev_rx/xdp_prog teardown race: __dev_flush() clears bq->dev_rx and bq->xdp_prog after bq_xmit_all(). If preempted between bq_xmit_all() return and bq->dev_rx = NULL, a preempting bq_enqueue() sees dev_rx still set (non-NULL), skips adding bq to the flush_list, and enqueues a frame. When __dev_flush() resumes, it clears dev_rx and removes bq from the flush_list, orphaning the newly enqueued frame. 4. __list_del_clearprev() on flush_node: similar to the cpumap race, both tasks can call __list_del_clearprev() on the same flush_node, the second dereferences the prev pointer already set to NULL. The race between task A (__dev_flush -> bq_xmit_all) and task B (bq_enqueue -> bq_xmit_all) on the same CPU: Task A (xdp_do_flush) Task B (ndo_xdp_xmit redirect) ---------------------- -------------------------------- __dev_flush(flush_list) bq_xmit_all(bq) cnt = bq->count /* e.g. 16 */ /* start iterating bq->q[] */ <-- CFS preempts Task A --> bq_enqueue(dev, xdpf) bq->count == DEV_MAP_BULK_SIZE bq_xmit_all(bq, 0) cnt = bq->count /* same 16! */ ndo_xdp_xmit(bq->q[]) /* frames freed by driver */ bq->count = 0 <-- Task A resumes --> ndo_xdp_xmit(bq->q[]) /* use-after-free: frames already freed! */ Fix this by adding a local_lock_t to xdp_dev_bulk_queue and acquiring it in bq_enqueue() and __dev_flush(). These paths already run under local_bh_disable(), so use local_lock_nested_bh() which on non-RT is a pure annotation with no overhead, and on PREEMPT_RT provides a per-CPU sleeping lock that serializes access to the bq. Fixes: 3253cb49cbad ("softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT") Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com> Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev> Link: https://lore.kernel.org/r/20260225121459.183121-3-jiayuan.chen@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
On PREEMPT_RT kernels, the per-CPU xdp_dev_bulk_queue (bq) can be
accessed concurrently by multiple preemptible tasks on the same CPU.

The original code assumes bq_enqueue() and __dev_flush() run atomically
with respect to each other on the same CPU, relying on
local_bh_disable() to prevent preemption. However, on PREEMPT_RT,
local_bh_disable() only calls migrate_disable() (when
PREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable
preemption, which allows CFS scheduling to preempt a task during
bq_xmit_all(), enabling another task on the same CPU to enter
bq_enqueue() and operate on the same per-CPU bq concurrently.

This leads to several races:

1. Double-free / use-after-free on bq->q[]: bq_xmit_all() snapshots
   cnt = bq->count, then iterates bq->q[0..cnt-1] to transmit frames.
   If preempted after the snapshot, a second task can call bq_enqueue()
   -> bq_xmit_all() on the same bq, transmitting (and freeing) the
   same frames. When the first task resumes, it operates on stale
   pointers in bq->q[], causing use-after-free.

2. bq->count and bq->q[] corruption: concurrent bq_enqueue() modifying
   bq->count and bq->q[] while bq_xmit_all() is reading them.

3. dev_rx/xdp_prog teardown race: __dev_flush() clears bq->dev_rx and
   bq->xdp_prog after bq_xmit_all(). If preempted between
   bq_xmit_all() return and bq->dev_rx = NULL, a preempting
   bq_enqueue() sees dev_rx still set (non-NULL), skips adding bq to
   the flush_list, and enqueues a frame. When __dev_flush() resumes,
   it clears dev_rx and removes bq from the flush_list, orphaning the
   newly enqueued frame.

4. __list_del_clearprev() on flush_node: similar to the cpumap race,
   both tasks can call __list_del_clearprev() on the same flush_node,
   the second dereferences the prev pointer already set to NULL.

The race between task A (__dev_flush -> bq_xmit_all) and task B
(bq_enqueue -> bq_xmit_all) on the same CPU:

  Task A (xdp_do_flush)          Task B (ndo_xdp_xmit redirect)
  ----------------------         --------------------------------
  __dev_flush(flush_list)
    bq_xmit_all(bq)
      cnt = bq->count  /* e.g. 16 */
      /* start iterating bq->q[] */
    <-- CFS preempts Task A -->
                                   bq_enqueue(dev, xdpf)
                                     bq->count == DEV_MAP_BULK_SIZE
                                     bq_xmit_all(bq, 0)
                                       cnt = bq->count  /* same 16! */
                                       ndo_xdp_xmit(bq->q[])
                                       /* frames freed by driver */
                                       bq->count = 0
    <-- Task A resumes -->
      ndo_xdp_xmit(bq->q[])
      /* use-after-free: frames already freed! */

Fix this by adding a local_lock_t to xdp_dev_bulk_queue and acquiring
it in bq_enqueue() and __dev_flush(). These paths already run under
local_bh_disable(), so use local_lock_nested_bh() which on non-RT is
a pure annotation with no overhead, and on PREEMPT_RT provides a
per-CPU sleeping lock that serializes access to the bq.

Fixes: 3253cb49cbad ("softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT")
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Link: https://lore.kernel.org/r/20260225121459.183121-3-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Fix stack-out-of-bounds write in devmap 2026-02-26T19:25:53+00:00 Kohei Enju kohei@enjuk.jp 2026-02-25T05:34:44+00:00 b7bf516c3ecd9a2aae2dc2635178ab87b734fef1 get_upper_ifindexes() iterates over all upper devices and writes their indices into an array without checking bounds. Also the callers assume that the max number of upper devices is MAX_NEST_DEV and allocate excluded_devices[1+MAX_NEST_DEV] on the stack, but that assumption is not correct and the number of upper devices could be larger than MAX_NEST_DEV (e.g., many macvlans), causing a stack-out-of-bounds write. Add a max parameter to get_upper_ifindexes() to avoid the issue. When there are too many upper devices, return -EOVERFLOW and abort the redirect. To reproduce, create more than MAX_NEST_DEV(8) macvlans on a device with an XDP program attached using BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS. Then send a packet to the device to trigger the XDP redirect path. Reported-by: syzbot+10cc7f13760b31bd2e61@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/698c4ce3.050a0220.340abe.000b.GAE@google.com/T/ Fixes: aeea1b86f936 ("bpf, devmap: Exclude XDP broadcast to master device") Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Kohei Enju <kohei@enjuk.jp> Link: https://lore.kernel.org/r/20260225053506.4738-1-kohei@enjuk.jp Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
get_upper_ifindexes() iterates over all upper devices and writes their
indices into an array without checking bounds.

Also the callers assume that the max number of upper devices is
MAX_NEST_DEV and allocate excluded_devices[1+MAX_NEST_DEV] on the stack,
but that assumption is not correct and the number of upper devices could
be larger than MAX_NEST_DEV (e.g., many macvlans), causing a
stack-out-of-bounds write.

Add a max parameter to get_upper_ifindexes() to avoid the issue.
When there are too many upper devices, return -EOVERFLOW and abort the
redirect.

To reproduce, create more than MAX_NEST_DEV(8) macvlans on a device with
an XDP program attached using BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS.
Then send a packet to the device to trigger the XDP redirect path.

Reported-by: syzbot+10cc7f13760b31bd2e61@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/698c4ce3.050a0220.340abe.000b.GAE@google.com/T/
Fixes: aeea1b86f936 ("bpf, devmap: Exclude XDP broadcast to master device")
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Kohei Enju <kohei@enjuk.jp>
Link: https://lore.kernel.org/r/20260225053506.4738-1-kohei@enjuk.jp
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Remove redundant __GFP_NOWARN 2025-08-12T21:56:04+00:00 Qianfeng Rong rongqianfeng@vivo.com 2025-08-04T12:27:30+00:00 3e2b799008a78c21c648328bed9f566335f0394e Commit 16f5dfbc851b ("gfp: include __GFP_NOWARN in GFP_NOWAIT") made GFP_NOWAIT implicitly include __GFP_NOWARN. Therefore, explicit __GFP_NOWARN combined with GFP_NOWAIT (e.g., `GFP_NOWAIT | __GFP_NOWARN`) is now redundant. Let's clean up these redundant flags across subsystems. No functional changes. Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/bpf/20250804122731.460158-1-rongqianfeng@vivo.com 
Commit 16f5dfbc851b ("gfp: include __GFP_NOWARN in GFP_NOWAIT")
made GFP_NOWAIT implicitly include __GFP_NOWARN.

Therefore, explicit __GFP_NOWARN combined with GFP_NOWAIT
(e.g., `GFP_NOWAIT | __GFP_NOWARN`) is now redundant. Let's clean
up these redundant flags across subsystems.

No functional changes.

Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20250804122731.460158-1-rongqianfeng@vivo.com
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-12-12T22:19:05+00:00 Jakub Kicinski kuba@kernel.org 2024-12-05T19:48:58+00:00 5098462fbac60cbec76171a8b4998a36b85891a1 Cross-merge networking fixes after downstream PR (net-6.13-rc3). No conflicts or adjacent changes. Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Cross-merge networking fixes after downstream PR (net-6.13-rc3).

No conflicts or adjacent changes.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
bpf, xdp: constify some bpf_prog * function arguments 2024-12-06T02:41:06+00:00 Alexander Lobakin aleksander.lobakin@intel.com 2024-12-03T17:37:25+00:00 7cd1107f48e2a246c6a628c2381e1b8aafa4675a In lots of places, bpf_prog pointer is used only for tracing or other stuff that doesn't modify the structure itself. Same for net_device. Address at least some of them and add `const` attributes there. The object code didn't change, but that may prevent unwanted data modifications and also allow more helpers to have const arguments. Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
In lots of places, bpf_prog pointer is used only for tracing or other
stuff that doesn't modify the structure itself. Same for net_device.
Address at least some of them and add `const` attributes there. The
object code didn't change, but that may prevent unwanted data
modifications and also allow more helpers to have const arguments.

Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
bpf: fix OOB devmap writes when deleting elements 2024-11-25T22:25:48+00:00 Maciej Fijalkowski maciej.fijalkowski@intel.com 2024-11-22T12:10:30+00:00 ab244dd7cf4c291f82faacdc50b45cc0f55b674d Jordy reported issue against XSKMAP which also applies to DEVMAP - the index used for accessing map entry, due to being a signed integer, causes the OOB writes. Fix is simple as changing the type from int to u32, however, when compared to XSKMAP case, one more thing needs to be addressed. When map is released from system via dev_map_free(), we iterate through all of the entries and an iterator variable is also an int, which implies OOB accesses. Again, change it to be u32. Example splat below: [ 160.724676] BUG: unable to handle page fault for address: ffffc8fc2c001000 [ 160.731662] #PF: supervisor read access in kernel mode [ 160.736876] #PF: error_code(0x0000) - not-present page [ 160.742095] PGD 0 P4D 0 [ 160.744678] Oops: Oops: 0000 [#1] PREEMPT SMP [ 160.749106] CPU: 1 UID: 0 PID: 520 Comm: kworker/u145:12 Not tainted 6.12.0-rc1+ #487 [ 160.757050] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019 [ 160.767642] Workqueue: events_unbound bpf_map_free_deferred [ 160.773308] RIP: 0010:dev_map_free+0x77/0x170 [ 160.777735] Code: 00 e8 fd 91 ed ff e8 b8 73 ed ff 41 83 7d 18 19 74 6e 41 8b 45 24 49 8b bd f8 00 00 00 31 db 85 c0 74 48 48 63 c3 48 8d 04 c7 <48> 8b 28 48 85 ed 74 30 48 8b 7d 18 48 85 ff 74 05 e8 b3 52 fa ff [ 160.796777] RSP: 0018:ffffc9000ee1fe38 EFLAGS: 00010202 [ 160.802086] RAX: ffffc8fc2c001000 RBX: 0000000080000000 RCX: 0000000000000024 [ 160.809331] RDX: 0000000000000000 RSI: 0000000000000024 RDI: ffffc9002c001000 [ 160.816576] RBP: 0000000000000000 R08: 0000000000000023 R09: 0000000000000001 [ 160.823823] R10: 0000000000000001 R11: 00000000000ee6b2 R12: dead000000000122 [ 160.831066] R13: ffff88810c928e00 R14: ffff8881002df405 R15: 0000000000000000 [ 160.838310] FS: 0000000000000000(0000) GS:ffff8897e0c40000(0000) knlGS:0000000000000000 [ 160.846528] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 160.852357] CR2: ffffc8fc2c001000 CR3: 0000000005c32006 CR4: 00000000007726f0 [ 160.859604] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 160.866847] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 160.874092] PKRU: 55555554 [ 160.876847] Call Trace: [ 160.879338] <TASK> [ 160.881477] ? __die+0x20/0x60 [ 160.884586] ? page_fault_oops+0x15a/0x450 [ 160.888746] ? search_extable+0x22/0x30 [ 160.892647] ? search_bpf_extables+0x5f/0x80 [ 160.896988] ? exc_page_fault+0xa9/0x140 [ 160.900973] ? asm_exc_page_fault+0x22/0x30 [ 160.905232] ? dev_map_free+0x77/0x170 [ 160.909043] ? dev_map_free+0x58/0x170 [ 160.912857] bpf_map_free_deferred+0x51/0x90 [ 160.917196] process_one_work+0x142/0x370 [ 160.921272] worker_thread+0x29e/0x3b0 [ 160.925082] ? rescuer_thread+0x4b0/0x4b0 [ 160.929157] kthread+0xd4/0x110 [ 160.932355] ? kthread_park+0x80/0x80 [ 160.936079] ret_from_fork+0x2d/0x50 [ 160.943396] ? kthread_park+0x80/0x80 [ 160.950803] ret_from_fork_asm+0x11/0x20 [ 160.958482] </TASK> Fixes: 546ac1ffb70d ("bpf: add devmap, a map for storing net device references") CC: stable@vger.kernel.org Reported-by: Jordy Zomer <jordyzomer@google.com> Suggested-by: Jordy Zomer <jordyzomer@google.com> Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com> Link: https://lore.kernel.org/r/20241122121030.716788-3-maciej.fijalkowski@intel.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Jordy reported issue against XSKMAP which also applies to DEVMAP - the
index used for accessing map entry, due to being a signed integer,
causes the OOB writes. Fix is simple as changing the type from int to
u32, however, when compared to XSKMAP case, one more thing needs to be
addressed.

When map is released from system via dev_map_free(), we iterate through
all of the entries and an iterator variable is also an int, which
implies OOB accesses. Again, change it to be u32.

Example splat below:

[  160.724676] BUG: unable to handle page fault for address: ffffc8fc2c001000
[  160.731662] #PF: supervisor read access in kernel mode
[  160.736876] #PF: error_code(0x0000) - not-present page
[  160.742095] PGD 0 P4D 0
[  160.744678] Oops: Oops: 0000 [#1] PREEMPT SMP
[  160.749106] CPU: 1 UID: 0 PID: 520 Comm: kworker/u145:12 Not tainted 6.12.0-rc1+ #487
[  160.757050] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019
[  160.767642] Workqueue: events_unbound bpf_map_free_deferred
[  160.773308] RIP: 0010:dev_map_free+0x77/0x170
[  160.777735] Code: 00 e8 fd 91 ed ff e8 b8 73 ed ff 41 83 7d 18 19 74 6e 41 8b 45 24 49 8b bd f8 00 00 00 31 db 85 c0 74 48 48 63 c3 48 8d 04 c7 <48> 8b 28 48 85 ed 74 30 48 8b 7d 18 48 85 ff 74 05 e8 b3 52 fa ff
[  160.796777] RSP: 0018:ffffc9000ee1fe38 EFLAGS: 00010202
[  160.802086] RAX: ffffc8fc2c001000 RBX: 0000000080000000 RCX: 0000000000000024
[  160.809331] RDX: 0000000000000000 RSI: 0000000000000024 RDI: ffffc9002c001000
[  160.816576] RBP: 0000000000000000 R08: 0000000000000023 R09: 0000000000000001
[  160.823823] R10: 0000000000000001 R11: 00000000000ee6b2 R12: dead000000000122
[  160.831066] R13: ffff88810c928e00 R14: ffff8881002df405 R15: 0000000000000000
[  160.838310] FS:  0000000000000000(0000) GS:ffff8897e0c40000(0000) knlGS:0000000000000000
[  160.846528] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  160.852357] CR2: ffffc8fc2c001000 CR3: 0000000005c32006 CR4: 00000000007726f0
[  160.859604] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  160.866847] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  160.874092] PKRU: 55555554
[  160.876847] Call Trace:
[  160.879338]  <TASK>
[  160.881477]  ? __die+0x20/0x60
[  160.884586]  ? page_fault_oops+0x15a/0x450
[  160.888746]  ? search_extable+0x22/0x30
[  160.892647]  ? search_bpf_extables+0x5f/0x80
[  160.896988]  ? exc_page_fault+0xa9/0x140
[  160.900973]  ? asm_exc_page_fault+0x22/0x30
[  160.905232]  ? dev_map_free+0x77/0x170
[  160.909043]  ? dev_map_free+0x58/0x170
[  160.912857]  bpf_map_free_deferred+0x51/0x90
[  160.917196]  process_one_work+0x142/0x370
[  160.921272]  worker_thread+0x29e/0x3b0
[  160.925082]  ? rescuer_thread+0x4b0/0x4b0
[  160.929157]  kthread+0xd4/0x110
[  160.932355]  ? kthread_park+0x80/0x80
[  160.936079]  ret_from_fork+0x2d/0x50
[  160.943396]  ? kthread_park+0x80/0x80
[  160.950803]  ret_from_fork_asm+0x11/0x20
[  160.958482]  </TASK>

Fixes: 546ac1ffb70d ("bpf: add devmap, a map for storing net device references")
CC: stable@vger.kernel.org
Reported-by: Jordy Zomer <jordyzomer@google.com>
Suggested-by: Jordy Zomer <jordyzomer@google.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/r/20241122121030.716788-3-maciej.fijalkowski@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: devmap: provide rxq after redirect 2024-10-02T20:48:26+00:00 Florian Kauer florian.kauer@linutronix.de 2024-09-11T08:41:18+00:00 ca9984c5f0ab3690d98b13937b2485a978c8dd73 rxq contains a pointer to the device from where the redirect happened. Currently, the BPF program that was executed after a redirect via BPF_MAP_TYPE_DEVMAP* does not have it set. This is particularly bad since accessing ingress_ifindex, e.g. SEC("xdp") int prog(struct xdp_md *pkt) { return bpf_redirect_map(&dev_redirect_map, 0, 0); } SEC("xdp/devmap") int prog_after_redirect(struct xdp_md *pkt) { bpf_printk("ifindex %i", pkt->ingress_ifindex); return XDP_PASS; } depends on access to rxq, so a NULL pointer gets dereferenced: <1>[ 574.475170] BUG: kernel NULL pointer dereference, address: 0000000000000000 <1>[ 574.475188] #PF: supervisor read access in kernel mode <1>[ 574.475194] #PF: error_code(0x0000) - not-present page <6>[ 574.475199] PGD 0 P4D 0 <4>[ 574.475207] Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI <4>[ 574.475217] CPU: 4 UID: 0 PID: 217 Comm: kworker/4:1 Not tainted 6.11.0-rc5-reduced-00859-g780801200300 #23 <4>[ 574.475226] Hardware name: Intel(R) Client Systems NUC13ANHi7/NUC13ANBi7, BIOS ANRPL357.0026.2023.0314.1458 03/14/2023 <4>[ 574.475231] Workqueue: mld mld_ifc_work <4>[ 574.475247] RIP: 0010:bpf_prog_5e13354d9cf5018a_prog_after_redirect+0x17/0x3c <4>[ 574.475257] Code: cc cc cc cc cc cc cc 80 00 00 00 cc cc cc cc cc cc cc cc f3 0f 1e fa 0f 1f 44 00 00 66 90 55 48 89 e5 f3 0f 1e fa 48 8b 57 20 <48> 8b 52 00 8b 92 e0 00 00 00 48 bf f8 a6 d5 c4 5d a0 ff ff be 0b <4>[ 574.475263] RSP: 0018:ffffa62440280c98 EFLAGS: 00010206 <4>[ 574.475269] RAX: ffffa62440280cd8 RBX: 0000000000000001 RCX: 0000000000000000 <4>[ 574.475274] RDX: 0000000000000000 RSI: ffffa62440549048 RDI: ffffa62440280ce0 <4>[ 574.475278] RBP: ffffa62440280c98 R08: 0000000000000002 R09: 0000000000000001 <4>[ 574.475281] R10: ffffa05dc8b98000 R11: ffffa05f577fca40 R12: ffffa05dcab24000 <4>[ 574.475285] R13: ffffa62440280ce0 R14: ffffa62440549048 R15: ffffa62440549000 <4>[ 574.475289] FS: 0000000000000000(0000) GS:ffffa05f4f700000(0000) knlGS:0000000000000000 <4>[ 574.475294] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 <4>[ 574.475298] CR2: 0000000000000000 CR3: 000000025522e000 CR4: 0000000000f50ef0 <4>[ 574.475303] PKRU: 55555554 <4>[ 574.475306] Call Trace: <4>[ 574.475313] <IRQ> <4>[ 574.475318] ? __die+0x23/0x70 <4>[ 574.475329] ? page_fault_oops+0x180/0x4c0 <4>[ 574.475339] ? skb_pp_cow_data+0x34c/0x490 <4>[ 574.475346] ? kmem_cache_free+0x257/0x280 <4>[ 574.475357] ? exc_page_fault+0x67/0x150 <4>[ 574.475368] ? asm_exc_page_fault+0x26/0x30 <4>[ 574.475381] ? bpf_prog_5e13354d9cf5018a_prog_after_redirect+0x17/0x3c <4>[ 574.475386] bq_xmit_all+0x158/0x420 <4>[ 574.475397] __dev_flush+0x30/0x90 <4>[ 574.475407] veth_poll+0x216/0x250 [veth] <4>[ 574.475421] __napi_poll+0x28/0x1c0 <4>[ 574.475430] net_rx_action+0x32d/0x3a0 <4>[ 574.475441] handle_softirqs+0xcb/0x2c0 <4>[ 574.475451] do_softirq+0x40/0x60 <4>[ 574.475458] </IRQ> <4>[ 574.475461] <TASK> <4>[ 574.475464] __local_bh_enable_ip+0x66/0x70 <4>[ 574.475471] __dev_queue_xmit+0x268/0xe40 <4>[ 574.475480] ? selinux_ip_postroute+0x213/0x420 <4>[ 574.475491] ? alloc_skb_with_frags+0x4a/0x1d0 <4>[ 574.475502] ip6_finish_output2+0x2be/0x640 <4>[ 574.475512] ? nf_hook_slow+0x42/0xf0 <4>[ 574.475521] ip6_finish_output+0x194/0x300 <4>[ 574.475529] ? __pfx_ip6_finish_output+0x10/0x10 <4>[ 574.475538] mld_sendpack+0x17c/0x240 <4>[ 574.475548] mld_ifc_work+0x192/0x410 <4>[ 574.475557] process_one_work+0x15d/0x380 <4>[ 574.475566] worker_thread+0x29d/0x3a0 <4>[ 574.475573] ? __pfx_worker_thread+0x10/0x10 <4>[ 574.475580] ? __pfx_worker_thread+0x10/0x10 <4>[ 574.475587] kthread+0xcd/0x100 <4>[ 574.475597] ? __pfx_kthread+0x10/0x10 <4>[ 574.475606] ret_from_fork+0x31/0x50 <4>[ 574.475615] ? __pfx_kthread+0x10/0x10 <4>[ 574.475623] ret_from_fork_asm+0x1a/0x30 <4>[ 574.475635] </TASK> <4>[ 574.475637] Modules linked in: veth br_netfilter bridge stp llc iwlmvm x86_pkg_temp_thermal iwlwifi efivarfs nvme nvme_core <4>[ 574.475662] CR2: 0000000000000000 <4>[ 574.475668] ---[ end trace 0000000000000000 ]--- Therefore, provide it to the program by setting rxq properly. Fixes: cb261b594b41 ("bpf: Run devmap xdp_prog on flush instead of bulk enqueue") Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Florian Kauer <florian.kauer@linutronix.de> Acked-by: Jakub Kicinski <kuba@kernel.org> Link: https://lore.kernel.org/r/20240911-devel-koalo-fix-ingress-ifindex-v4-1-5c643ae10258@linutronix.de Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> 
rxq contains a pointer to the device from where
the redirect happened. Currently, the BPF program
that was executed after a redirect via BPF_MAP_TYPE_DEVMAP*
does not have it set.

This is particularly bad since accessing ingress_ifindex, e.g.

SEC("xdp")
int prog(struct xdp_md *pkt)
{
        return bpf_redirect_map(&dev_redirect_map, 0, 0);
}

SEC("xdp/devmap")
int prog_after_redirect(struct xdp_md *pkt)
{
        bpf_printk("ifindex %i", pkt->ingress_ifindex);
        return XDP_PASS;
}

depends on access to rxq, so a NULL pointer gets dereferenced:

<1>[  574.475170] BUG: kernel NULL pointer dereference, address: 0000000000000000
<1>[  574.475188] #PF: supervisor read access in kernel mode
<1>[  574.475194] #PF: error_code(0x0000) - not-present page
<6>[  574.475199] PGD 0 P4D 0
<4>[  574.475207] Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI
<4>[  574.475217] CPU: 4 UID: 0 PID: 217 Comm: kworker/4:1 Not tainted 6.11.0-rc5-reduced-00859-g780801200300 #23
<4>[  574.475226] Hardware name: Intel(R) Client Systems NUC13ANHi7/NUC13ANBi7, BIOS ANRPL357.0026.2023.0314.1458 03/14/2023
<4>[  574.475231] Workqueue: mld mld_ifc_work
<4>[  574.475247] RIP: 0010:bpf_prog_5e13354d9cf5018a_prog_after_redirect+0x17/0x3c
<4>[  574.475257] Code: cc cc cc cc cc cc cc 80 00 00 00 cc cc cc cc cc cc cc cc f3 0f 1e fa 0f 1f 44 00 00 66 90 55 48 89 e5 f3 0f 1e fa 48 8b 57 20 <48> 8b 52 00 8b 92 e0 00 00 00 48 bf f8 a6 d5 c4 5d a0 ff ff be 0b
<4>[  574.475263] RSP: 0018:ffffa62440280c98 EFLAGS: 00010206
<4>[  574.475269] RAX: ffffa62440280cd8 RBX: 0000000000000001 RCX: 0000000000000000
<4>[  574.475274] RDX: 0000000000000000 RSI: ffffa62440549048 RDI: ffffa62440280ce0
<4>[  574.475278] RBP: ffffa62440280c98 R08: 0000000000000002 R09: 0000000000000001
<4>[  574.475281] R10: ffffa05dc8b98000 R11: ffffa05f577fca40 R12: ffffa05dcab24000
<4>[  574.475285] R13: ffffa62440280ce0 R14: ffffa62440549048 R15: ffffa62440549000
<4>[  574.475289] FS:  0000000000000000(0000) GS:ffffa05f4f700000(0000) knlGS:0000000000000000
<4>[  574.475294] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4>[  574.475298] CR2: 0000000000000000 CR3: 000000025522e000 CR4: 0000000000f50ef0
<4>[  574.475303] PKRU: 55555554
<4>[  574.475306] Call Trace:
<4>[  574.475313]  <IRQ>
<4>[  574.475318]  ? __die+0x23/0x70
<4>[  574.475329]  ? page_fault_oops+0x180/0x4c0
<4>[  574.475339]  ? skb_pp_cow_data+0x34c/0x490
<4>[  574.475346]  ? kmem_cache_free+0x257/0x280
<4>[  574.475357]  ? exc_page_fault+0x67/0x150
<4>[  574.475368]  ? asm_exc_page_fault+0x26/0x30
<4>[  574.475381]  ? bpf_prog_5e13354d9cf5018a_prog_after_redirect+0x17/0x3c
<4>[  574.475386]  bq_xmit_all+0x158/0x420
<4>[  574.475397]  __dev_flush+0x30/0x90
<4>[  574.475407]  veth_poll+0x216/0x250 [veth]
<4>[  574.475421]  __napi_poll+0x28/0x1c0
<4>[  574.475430]  net_rx_action+0x32d/0x3a0
<4>[  574.475441]  handle_softirqs+0xcb/0x2c0
<4>[  574.475451]  do_softirq+0x40/0x60
<4>[  574.475458]  </IRQ>
<4>[  574.475461]  <TASK>
<4>[  574.475464]  __local_bh_enable_ip+0x66/0x70
<4>[  574.475471]  __dev_queue_xmit+0x268/0xe40
<4>[  574.475480]  ? selinux_ip_postroute+0x213/0x420
<4>[  574.475491]  ? alloc_skb_with_frags+0x4a/0x1d0
<4>[  574.475502]  ip6_finish_output2+0x2be/0x640
<4>[  574.475512]  ? nf_hook_slow+0x42/0xf0
<4>[  574.475521]  ip6_finish_output+0x194/0x300
<4>[  574.475529]  ? __pfx_ip6_finish_output+0x10/0x10
<4>[  574.475538]  mld_sendpack+0x17c/0x240
<4>[  574.475548]  mld_ifc_work+0x192/0x410
<4>[  574.475557]  process_one_work+0x15d/0x380
<4>[  574.475566]  worker_thread+0x29d/0x3a0
<4>[  574.475573]  ? __pfx_worker_thread+0x10/0x10
<4>[  574.475580]  ? __pfx_worker_thread+0x10/0x10
<4>[  574.475587]  kthread+0xcd/0x100
<4>[  574.475597]  ? __pfx_kthread+0x10/0x10
<4>[  574.475606]  ret_from_fork+0x31/0x50
<4>[  574.475615]  ? __pfx_kthread+0x10/0x10
<4>[  574.475623]  ret_from_fork_asm+0x1a/0x30
<4>[  574.475635]  </TASK>
<4>[  574.475637] Modules linked in: veth br_netfilter bridge stp llc iwlmvm x86_pkg_temp_thermal iwlwifi efivarfs nvme nvme_core
<4>[  574.475662] CR2: 0000000000000000
<4>[  574.475668] ---[ end trace 0000000000000000 ]---

Therefore, provide it to the program by setting rxq properly.

Fixes: cb261b594b41 ("bpf: Run devmap xdp_prog on flush instead of bulk enqueue")
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Florian Kauer <florian.kauer@linutronix.de>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20240911-devel-koalo-fix-ingress-ifindex-v4-1-5c643ae10258@linutronix.de
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>