Daniel Borkmann (1): bpf: Reject a store through a fault prone pointer Kumar Kartikeya Dwivedi (2): bpf: Mark sched_process_wait argument as nullable bpf: Mark signal tracepoint siginfo arguments as scalar include/linux/bpf_verifier.h | 10 ++++++++++ kernel/bpf/btf.c | 7 +++++++ kernel/bpf/verifier.c | 2 +- 3 files changed, 18 insertions(+), 1 deletion(-) -- 2.34.1
From: Kumar Kartikeya Dwivedi <memxor@gmail.com> mainline inclusion from mainline-v7.3-rc2 commit a453d6e3b8e8e1a321c8744d6189d763af9287d0 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/10047 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- do_wait() passes wo->wo_pid to the sched_process_wait tracepoint. kernel_wait4() leaves wo_pid NULL for wait4(-1), and kernel_waitid_prepare() does likewise for waitid(P_ALL). btf_ctx_access() currently types argument 0 as PTR_TO_BTF_ID | PTR_TRUSTED. Without PTR_MAYBE_NULL, the verifier accepts an unchecked dereference. Trusted pointer loads have no fault protection, so a wait for any child can then cause a NULL pointer dereference in JITed BPF code. Add sched_process_wait to raw_tp_null_args[] with argument 0 marked nullable. The verifier rejects an unchecked dereference while preserving access after the program checks the pointer for NULL. Fixes: 838a10bd2ebf ("bpf: Augment raw_tp arguments with PTR_MAYBE_NULL") Reported-by: Nicholas Carlini <npc@anthropic.com> Suggested-by: Nicholas Carlini <npc@anthropic.com> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20260903144433.1716731-8-memxor@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Pu Lehui <pulehui@huawei.com> --- kernel/bpf/btf.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 734e2858ac8a..5e02871ea112 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6036,6 +6036,10 @@ struct bpf_raw_tp_null_args { static const struct bpf_raw_tp_null_args raw_tp_null_args[] = { /* sched */ { "sched_pi_setprio", 0x10 }, + /* + * do_wait() passes NULL for wait4(-1) and waitid(P_ALL). + */ + { "sched_process_wait", 0x1 }, /* ... from sched_numa_pair_template event class */ { "sched_stick_numa", 0x100 }, { "sched_swap_numa", 0x100 }, -- 2.34.1
From: Kumar Kartikeya Dwivedi <memxor@gmail.com> mainline inclusion from mainline-v7.3-rc2 commit 77515ab12e4983e6416f8c35039a3f0c0822ac70 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/10047 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- The signal_generate and signal_deliver tracepoints declare their info argument as a struct kernel_siginfo pointer. btf_ctx_access() therefore treats it as a trusted pointer for tp_btf programs. Signal delivery also uses SEND_SIG_NOINFO and SEND_SIG_PRIV as special values for this argument. Those values are zero and one respectively, and are not pointers. A tp_btf program can currently dereference either value and fault the kernel. In particular, signal_generate can run from timer interrupt context, turning the fault into a kernel panic. Record both tracepoints in raw_tp_null_args[] and mark argument one as a non-pointer. This preserves scalar access to the cookie while rejecting direct and helper-mediated pointer use. Merely marking it nullable would not suffice because SEND_SIG_PRIV is nonzero. Fixes: 838a10bd2ebf ("bpf: Augment raw_tp arguments with PTR_MAYBE_NULL") Reported-by: Nicholas Carlini <npc@anthropic.com> Suggested-by: Nicholas Carlini <npc@anthropic.com> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20260903144433.1716731-2-memxor@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Conflicts: kernel/bpf/btf.c [ctx conflicts] Signed-off-by: Pu Lehui <pulehui@huawei.com> --- kernel/bpf/btf.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 5e02871ea112..2962c6d17ba9 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6107,6 +6107,9 @@ static const struct bpf_raw_tp_null_args raw_tp_null_args[] = { { "rxrpc_resend", 0x10 }, { "rxrpc_tq", 0x10 }, { "rxrpc_client", 0x1 }, + /* signal */ + { "signal_generate", 0x20 }, + { "signal_deliver", 0x20 }, /* sunrpc */ { "xs_stream_read_data", 0x1 }, /* ... from xprt_cong_event event class */ -- 2.34.1
From: Daniel Borkmann <daniel@iogearbox.net> mainline inclusion from mainline-v7.3-rc2 commit ee9ad135b2087f9335eed97d062f5853e70f89fe category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/10047 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- check_ptr_to_btf_access() allows the program to store before the default BTF access path gets to reject a non read access. ac65c710cc64 ("bpf: Reject writes through untrusted BTF pointers") closed that for a PTR_UNTRUSTED pointer, but a bare PTR_TO_BTF_ID may fault on a dereference just the same and is let through. A BPF_LDX gets the BPF_PROBE_MEM rewrite in bpf_convert_ctx_accesses() and a bad address is handled, but a BPF_STX does not and cannot, there is no probed store to rewrite. The store is emitted as a plain one without an exception table entry and a bad address panics the kernel. A bpf_qdisc program can reach this, bpf_qdisc_btf_struct_access() permits a write to Qdisc::limit and Qdisc::next_sched is a plain struct Qdisc pointer which the walk turns into the compat type: struct Qdisc *next = sch->next_sched; next->limit = 1000; BUG: kernel NULL pointer dereference, address: 0000000000000014 RIP: 0010:bpf_prog_c6e14e7f32c8e325_bpf_fifo_enqueue+0x3a/0x12b Code: [...] bf e8 03 00 00 <89> 7e 14 41 8b 7f 14 [...] Kernel panic - not syncing: Fatal exception in interrupt Fix by widen the check to bpf_may_fault_on_deref() so that it covers both. Fixes: 27ae7997a661 ("bpf: Introduce BPF_PROG_TYPE_STRUCT_OPS") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20260814215301.709827-3-daniel@iogearbox.net Conflicts: include/linux/bpf_verifier.h [Add bpf_may_fault_on_deref helper] Signed-off-by: Pu Lehui <pulehui@huawei.com> --- include/linux/bpf_verifier.h | 10 ++++++++++ kernel/bpf/verifier.c | 2 +- 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index eeef504067e6..6e8b9391a631 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -840,6 +840,16 @@ static inline u32 type_flag(u32 type) return type & ~BPF_BASE_TYPE_MASK; } +static inline bool bpf_may_fault_on_deref(enum bpf_reg_type type) +{ + /* + * The pointer types which must not be dereferenced without fault + * protection, that is, the ones bpf_convert_ctx_accesses() has to + * turn a BPF_LDX into a BPF_PROBE_MEM one for. + */ + return type == PTR_TO_BTF_ID || (type_flag(type) & PTR_UNTRUSTED); +} + /* only use after check_attach_btf_id() */ static inline enum bpf_prog_type resolve_prog_type(const struct bpf_prog *prog) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9b2008aab1ea..f46aad9c9b47 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6602,7 +6602,7 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env, return -EACCES; } - if (atype != BPF_READ && (type_flag(reg->type) & PTR_UNTRUSTED)) { + if (atype != BPF_READ && bpf_may_fault_on_deref(reg->type)) { verbose(env, "only read is supported\n"); return -EACCES; } -- 2.34.1
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