The usage pattern for widen_imprecise_scalars() looks as follows:

    prev_st = find_prev_entry(env, ...);
    queued_st = push_stack(...);
    widen_imprecise_scalars(env, prev_st, queued_st);

Where prev_st is an ancestor of the queued_st in the explored states
tree. This ancestor is not guaranteed to have same allocated stack
depth as queued_st. E.g. in the following case:

    def main():
      for i in 1..2:
        foo(i)        // same callsite, differnt param

    def foo(i):
      if i == 1:
        use 128 bytes of stack
      iterator based loop

Here, for a second 'foo' call prev_st->allocated_stack is 128,
while queued_st->allocated_stack is much smaller.
widen_imprecise_scalars() needs to take this into account and avoid
accessing bpf_verifier_state->frame[*]->stack out of bounds.

Fixes: 2793a8b015f7 ("bpf: exact states comparison for iterator convergence checks")
Reported-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251114025730.772723-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Rename:
bpf_task_work_schedule_resume()->bpf_task_work_schedule_resume_impl()
bpf_task_work_schedule_signal()->bpf_task_work_schedule_signal_impl()

This aligns task work scheduling kfuncs with the established naming
scheme for kfuncs with the bpf_prog_aux argument provided by the
verifier implicitly. This convention will be taken advantage of with the
upcoming KF_IMPLICIT_ARGS feature to preserve backwards compatibility to
BPF programs.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20251104-implv2-v3-1-4772b9ae0e06@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>

When verifying BPF programs, the check_alu_op() function validates
instructions with ALU operations. The 'offset' field in these
instructions is a signed 16-bit integer.

The existing check 'insn->off > 1' was intended to ensure the offset is
either 0, or 1 for BPF_MOD/BPF_DIV. However, because 'insn->off' is
signed, this check incorrectly accepts all negative values (e.g., -1).

This commit tightens the validation by changing the condition to
'(insn->off != 0 && insn->off != 1)'. This ensures that any value
other than the explicitly permitted 0 and 1 is rejected, hardening the
verifier against malformed BPF programs.

Co-developed-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Signed-off-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Co-developed-by: Tianci Cao <ziye@zju.edu.cn>
Signed-off-by: Tianci Cao <ziye@zju.edu.cn>
Signed-off-by: Yazhou Tang <tangyazhou518@outlook.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Fixes: ec0e2da95f72 ("bpf: Support new signed div/mod instructions.")
Link: https://lore.kernel.org/r/tencent_70D024BAE70A0A309A4781694C7B764B0608@qq.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

In check_alu_op(), the verifier currently calls check_reg_arg() and
adjust_scalar_min_max_vals() unconditionally for BPF_NEG operations.
However, if the destination register holds a pointer, these scalar
adjustments are unnecessary and potentially incorrect.

This patch adds a check to skip the adjustment logic when the destination
register contains a pointer.

Reported-by: syzbot+d36d5ae81e1b0a53ef58@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d36d5ae81e1b0a53ef58
Fixes: aced132599b3 ("bpf: Add range tracking for BPF_NEG")
Suggested-by: KaFai Wan <kafai.wan@linux.dev>
Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Brahmajit Das <listout@listout.xyz>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251001191739.2323644-2-listout@listout.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Pull bpf updates from Alexei Starovoitov:

 - Support pulling non-linear xdp data with bpf_xdp_pull_data() kfunc
   (Amery Hung)

   Applied as a stable branch in bpf-next and net-next trees.

 - Support reading skb metadata via bpf_dynptr (Jakub Sitnicki)

   Also a stable branch in bpf-next and net-next trees.

 - Enforce expected_attach_type for tailcall compatibility (Daniel
   Borkmann)

 - Replace path-sensitive with path-insensitive live stack analysis in
   the verifier (Eduard Zingerman)

   This is a significant change in the verification logic. More details,
   motivation, long term plans are in the cover letter/merge commit.

 - Support signed BPF programs (KP Singh)

   This is another major feature that took years to materialize.

   Algorithm details are in the cover letter/marge commit

 - Add support for may_goto instruction to s390 JIT (Ilya Leoshkevich)

 - Add support for may_goto instruction to arm64 JIT (Puranjay Mohan)

 - Fix USDT SIB argument handling in libbpf (Jiawei Zhao)

 - Allow uprobe-bpf program to change context registers (Jiri Olsa)

 - Support signed loads from BPF arena (Kumar Kartikeya Dwivedi and
   Puranjay Mohan)

 - Allow access to union arguments in tracing programs (Leon Hwang)

 - Optimize rcu_read_lock() + migrate_disable() combination where it's
   used in BPF subsystem (Menglong Dong)

 - Introduce bpf_task_work_schedule*() kfuncs to schedule deferred
   execution of BPF callback in the context of a specific task using the
   kernel’s task_work infrastructure (Mykyta Yatsenko)

 - Enforce RCU protection for KF_RCU_PROTECTED kfuncs (Kumar Kartikeya
   Dwivedi)

 - Add stress test for rqspinlock in NMI (Kumar Kartikeya Dwivedi)

 - Improve the precision of tnum multiplier verifier operation
   (Nandakumar Edamana)

 - Use tnums to improve is_branch_taken() logic (Paul Chaignon)

 - Add support for atomic operations in arena in riscv JIT (Pu Lehui)

 - Report arena faults to BPF error stream (Puranjay Mohan)

 - Search for tracefs at /sys/kernel/tracing first in bpftool (Quentin
   Monnet)

 - Add bpf_strcasecmp() kfunc (Rong Tao)

 - Support lookup_and_delete_elem command in BPF_MAP_STACK_TRACE (Tao
   Chen)

* tag 'bpf-next-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (197 commits)
  libbpf: Replace AF_ALG with open coded SHA-256
  selftests/bpf: Add stress test for rqspinlock in NMI
  selftests/bpf: Add test case for different expected_attach_type
  bpf: Enforce expected_attach_type for tailcall compatibility
  bpftool: Remove duplicate string.h header
  bpf: Remove duplicate crypto/sha2.h header
  libbpf: Fix error when st-prefix_ops and ops from differ btf
  selftests/bpf: Test changing packet data from kfunc
  selftests/bpf: Add stacktrace map lookup_and_delete_elem test case
  selftests/bpf: Refactor stacktrace_map case with skeleton
  bpf: Add lookup_and_delete_elem for BPF_MAP_STACK_TRACE
  selftests/bpf: Fix flaky bpf_cookie selftest
  selftests/bpf: Test changing packet data from global functions with a kfunc
  bpf: Emit struct bpf_xdp_sock type in vmlinux BTF
  selftests/bpf: Task_work selftest cleanup fixes
  MAINTAINERS: Delete inactive maintainers from AF_XDP
  bpf: Mark kfuncs as __noclone
  selftests/bpf: Add kprobe multi write ctx attach test
  selftests/bpf: Add kprobe write ctx attach test
  selftests/bpf: Add uprobe context ip register change test
  ...

Pull scheduler updates from Ingo Molnar:
 "Core scheduler changes:

   - Make migrate_{en,dis}able() inline, to improve performance
     (Menglong Dong)

   - Move STDL_INIT() functions out-of-line (Peter Zijlstra)

   - Unify the SCHED_{SMT,CLUSTER,MC} Kconfig (Peter Zijlstra)

  Fair scheduling:

   - Defer throttling to when tasks exit to user-space, to reduce the
     chance & impact of throttle-preemption with held locks and other
     resources (Aaron Lu, Valentin Schneider)

   - Get rid of sched_domains_curr_level hack for tl->cpumask(), as the
     warning was getting triggered on certain topologies (Peter
     Zijlstra)

  Misc cleanups & fixes:

   - Header cleanups (Menglong Dong)

   - Fix race in push_dl_task() (Harshit Agarwal)"

* tag 'sched-core-2025-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix some typos in include/linux/preempt.h
  sched: Make migrate_{en,dis}able() inline
  rcu: Replace preempt.h with sched.h in include/linux/rcupdate.h
  arch: Add the macro COMPILE_OFFSETS to all the asm-offsets.c
  sched/fair: Do not balance task to a throttled cfs_rq
  sched/fair: Do not special case tasks in throttled hierarchy
  sched/fair: update_cfs_group() for throttled cfs_rqs
  sched/fair: Propagate load for throttled cfs_rq
  sched/fair: Get rid of throttled_lb_pair()
  sched/fair: Task based throttle time accounting
  sched/fair: Switch to task based throttle model
  sched/fair: Implement throttle task work and related helpers
  sched/fair: Add related data structure for task based throttle
  sched: Unify the SCHED_{SMT,CLUSTER,MC} Kconfig
  sched: Move STDL_INIT() functions out-of-line
  sched/fair: Get rid of sched_domains_curr_level hack for tl->cpumask()
  sched/deadline: Fix race in push_dl_task()

For now, migrate_enable and migrate_disable are global, which makes them
become hotspots in some case. Take BPF for example, the function calling
to migrate_enable and migrate_disable in BPF trampoline can introduce
significant overhead, and following is the 'perf top' of FENTRY's
benchmark (./tools/testing/selftests/bpf/bench trig-fentry):

  54.63% bpf_prog_2dcccf652aac1793_bench_trigger_fentry [k]
                 bpf_prog_2dcccf652aac1793_bench_trigger_fentry
  10.43% [kernel] [k] migrate_enable
  10.07% bpf_trampoline_6442517037 [k] bpf_trampoline_6442517037
  8.06% [kernel] [k] __bpf_prog_exit_recur
  4.11% libc.so.6 [.] syscall
  2.15% [kernel] [k] entry_SYSCALL_64
  1.48% [kernel] [k] memchr_inv
  1.32% [kernel] [k] fput
  1.16% [kernel] [k] _copy_to_user
  0.73% [kernel] [k] bpf_prog_test_run_raw_tp

So in this commit, we make migrate_enable/migrate_disable inline to obtain
better performance. The struct rq is defined internally in
kernel/sched/sched.h, and the field "nr_pinned" is accessed in
migrate_enable/migrate_disable, which makes it hard to make them inline.

Alexei Starovoitov suggests to generate the offset of "nr_pinned" in [1],
so we can define the migrate_enable/migrate_disable in
include/linux/sched.h and access "this_rq()->nr_pinned" with
"(void *)this_rq() + RQ_nr_pinned".

The offset of "nr_pinned" is generated in include/generated/rq-offsets.h
by kernel/sched/rq-offsets.c.

Generally speaking, we move the definition of migrate_enable and
migrate_disable to include/linux/sched.h from kernel/sched/core.c. The
calling to __set_cpus_allowed_ptr() is leaved in ___migrate_enable().

The "struct rq" is not available in include/linux/sched.h, so we can't
access the "runqueues" with this_cpu_ptr(), as the compilation will fail
in this_cpu_ptr() -> raw_cpu_ptr() -> __verify_pcpu_ptr():
  typeof((ptr) + 0)

So we introduce the this_rq_raw() and access the runqueues with
arch_raw_cpu_ptr/PERCPU_PTR directly.

The variable "runqueues" is not visible in the kernel modules, and export
it is not a good idea. As Peter Zijlstra advised in [2], we define and
export migrate_enable/migrate_disable in kernel/sched/core.c too, and use
them for the modules.

Before this patch, the performance of BPF FENTRY is:

  fentry         :  113.030 ± 0.149M/s
  fentry         :  112.501 ± 0.187M/s
  fentry         :  112.828 ± 0.267M/s
  fentry         :  115.287 ± 0.241M/s

After this patch, the performance of BPF FENTRY increases to:

  fentry         :  143.644 ± 0.670M/s
  fentry         :  149.764 ± 0.362M/s
  fentry         :  149.642 ± 0.156M/s
  fentry         :  145.263 ± 0.221M/s

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/bpf/CAADnVQ+5sEDKHdsJY5ZsfGDO_1SEhhQWHrt2SMBG5SYyQ+jt7w@mail.gmail.com/ [1]
Link: https://lore.kernel.org/all/20250819123214.GH4067720@noisy.programming.kicks-ass.net/ [2]

Merge the xdp_pull_data stable branch into the master branch. No conflict.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf_xdp_pull_data() may change packet data and therefore packet pointers
need to be invalidated. Add bpf_xdp_pull_data() to the special kfunc
list instead of introducing a new KF_ flag until there are more kfuncs
changing packet data.

Signed-off-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20250922233356.3356453-5-ameryhung@gmail.com

Currently, signed load instructions into arena memory are unsupported.
The compiler is free to generate these, and on GCC-14 we see a
corresponding error when it happens. The hurdle in supporting them is
deciding which unused opcode to use to mark them for the JIT's own
consumption. After much thinking, it appears 0xc0 / BPF_NOSPEC can be
combined with load instructions to identify signed arena loads. Use
this to recognize and JIT them appropriately, and remove the verifier
side limitation on the program if the JIT supports them.

Co-developed-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20250923110157.18326-2-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>