Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Pull bpf fixes from Alexei Starovoitov:

 - Fix how linked registers track zero extension of subregisters (Daniel
   Borkmann)

 - Fix unsound scalar fork for OR instructions (Daniel Wade)

 - Fix exception exit lock check for subprogs (Ihor Solodrai)

 - Fix undefined behavior in interpreter for SDIV/SMOD instructions
   (Jenny Guanni Qu)

 - Release module's BTF when module is unloaded (Kumar Kartikeya
   Dwivedi)

 - Fix constant blinding for PROBE_MEM32 instructions (Sachin Kumar)

 - Reset register ID for END instructions to prevent incorrect value
   tracking (Yazhou Tang)

* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  selftests/bpf: Add a test cases for sync_linked_regs regarding zext propagation
  bpf: Fix sync_linked_regs regarding BPF_ADD_CONST32 zext propagation
  selftests/bpf: Add tests for maybe_fork_scalars() OR vs AND handling
  bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR
  selftests/bpf: Add tests for sdiv32/smod32 with INT_MIN dividend
  bpf: Fix undefined behavior in interpreter sdiv/smod for INT_MIN
  selftests/bpf: Add tests for bpf_throw lock leak from subprogs
  bpf: Fix exception exit lock checking for subprogs
  bpf: Release module BTF IDR before module unload
  selftests/bpf: Fix pkg-config call on static builds
  bpf: Fix constant blinding for PROBE_MEM32 stores
  selftests/bpf: Add test for BPF_END register ID reset
  bpf: Reset register ID for BPF_END value tracking

3 files changed, 80 insertions, 20 deletions

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 4872d2a6c42d..71f9143fe90f 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -1787,7 +1787,16 @@ static void btf_free_id(struct btf *btf)
 	 * of the _bh() version.
 	 */
 	spin_lock_irqsave(&btf_idr_lock, flags);
-	idr_remove(&btf_idr, btf->id);
+	if (btf->id) {
+		idr_remove(&btf_idr, btf->id);
+		/*
+		 * Clear the id here to make this function idempotent, since it will get
+		 * called a couple of times for module BTFs: on module unload, and then
+		 * the final btf_put(). btf_alloc_id() starts IDs with 1, so we can use
+		 * 0 as sentinel value.
+		 */
+		WRITE_ONCE(btf->id, 0);
+	}
 	spin_unlock_irqrestore(&btf_idr_lock, flags);
 }
 
@@ -8115,7 +8124,7 @@ static void bpf_btf_show_fdinfo(struct seq_file *m, struct file *filp)
 {
 	const struct btf *btf = filp->private_data;
 
-	seq_printf(m, "btf_id:\t%u\n", btf->id);
+	seq_printf(m, "btf_id:\t%u\n", READ_ONCE(btf->id));
 }
 #endif
 
@@ -8197,7 +8206,7 @@ int btf_get_info_by_fd(const struct btf *btf,
 	if (copy_from_user(&info, uinfo, info_copy))
 		return -EFAULT;
 
-	info.id = btf->id;
+	info.id = READ_ONCE(btf->id);
 	ubtf = u64_to_user_ptr(info.btf);
 	btf_copy = min_t(u32, btf->data_size, info.btf_size);
 	if (copy_to_user(ubtf, btf->data, btf_copy))
@@ -8260,7 +8269,7 @@ int btf_get_fd_by_id(u32 id)
 
 u32 btf_obj_id(const struct btf *btf)
 {
-	return btf->id;
+	return READ_ONCE(btf->id);
 }
 
 bool btf_is_kernel(const struct btf *btf)
@@ -8382,6 +8391,13 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op,
 			if (btf_mod->module != module)
 				continue;
 
+			/*
+			 * For modules, we do the freeing of BTF IDR as soon as
+			 * module goes away to disable BTF discovery, since the
+			 * btf_try_get_module() on such BTFs will fail. This may
+			 * be called again on btf_put(), but it's ok to do so.
+			 */
+			btf_free_id(btf_mod->btf);
 			list_del(&btf_mod->list);
 			if (btf_mod->sysfs_attr)
 				sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr);
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 3ece2da55625..7b675a451ec8 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1422,6 +1422,27 @@ static int bpf_jit_blind_insn(const struct bpf_insn *from,
 		*to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
 		*to++ = BPF_STX_MEM(from->code, from->dst_reg, BPF_REG_AX, from->off);
 		break;
+
+	case BPF_ST | BPF_PROBE_MEM32 | BPF_DW:
+	case BPF_ST | BPF_PROBE_MEM32 | BPF_W:
+	case BPF_ST | BPF_PROBE_MEM32 | BPF_H:
+	case BPF_ST | BPF_PROBE_MEM32 | BPF_B:
+		*to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^
+				      from->imm);
+		*to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
+		/*
+		 * Cannot use BPF_STX_MEM() macro here as it
+		 * hardcodes BPF_MEM mode, losing PROBE_MEM32
+		 * and breaking arena addressing in the JIT.
+		 */
+		*to++ = (struct bpf_insn) {
+			.code  = BPF_STX | BPF_PROBE_MEM32 |
+				 BPF_SIZE(from->code),
+			.dst_reg = from->dst_reg,
+			.src_reg = BPF_REG_AX,
+			.off   = from->off,
+		};
+		break;
 	}
 out:
 	return to - to_buff;
@@ -1736,6 +1757,12 @@ bool bpf_opcode_in_insntable(u8 code)
 }
 
 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
+/* Absolute value of s32 without undefined behavior for S32_MIN */
+static u32 abs_s32(s32 x)
+{
+	return x >= 0 ? (u32)x : -(u32)x;
+}
+
 /**
  *	___bpf_prog_run - run eBPF program on a given context
  *	@regs: is the array of MAX_BPF_EXT_REG eBPF pseudo-registers
@@ -1900,8 +1927,8 @@ select_insn:
 			DST = do_div(AX, (u32) SRC);
 			break;
 		case 1:
-			AX = abs((s32)DST);
-			AX = do_div(AX, abs((s32)SRC));
+			AX = abs_s32((s32)DST);
+			AX = do_div(AX, abs_s32((s32)SRC));
 			if ((s32)DST < 0)
 				DST = (u32)-AX;
 			else
@@ -1928,8 +1955,8 @@ select_insn:
 			DST = do_div(AX, (u32) IMM);
 			break;
 		case 1:
-			AX = abs((s32)DST);
-			AX = do_div(AX, abs((s32)IMM));
+			AX = abs_s32((s32)DST);
+			AX = do_div(AX, abs_s32((s32)IMM));
 			if ((s32)DST < 0)
 				DST = (u32)-AX;
 			else
@@ -1955,8 +1982,8 @@ select_insn:
 			DST = (u32) AX;
 			break;
 		case 1:
-			AX = abs((s32)DST);
-			do_div(AX, abs((s32)SRC));
+			AX = abs_s32((s32)DST);
+			do_div(AX, abs_s32((s32)SRC));
 			if (((s32)DST < 0) == ((s32)SRC < 0))
 				DST = (u32)AX;
 			else
@@ -1982,8 +2009,8 @@ select_insn:
 			DST = (u32) AX;
 			break;
 		case 1:
-			AX = abs((s32)DST);
-			do_div(AX, abs((s32)IMM));
+			AX = abs_s32((s32)DST);
+			do_div(AX, abs_s32((s32)IMM));
 			if (((s32)DST < 0) == ((s32)IMM < 0))
 				DST = (u32)AX;
 			else
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 159b25f8269d..f108c01ff6d0 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -15910,6 +15910,13 @@ static void scalar_byte_swap(struct bpf_reg_state *dst_reg, struct bpf_insn *ins
 	/* Apply bswap if alu64 or switch between big-endian and little-endian machines */
 	bool need_bswap = alu64 || (to_le == is_big_endian);
 
+	/*
+	 * If the register is mutated, manually reset its scalar ID to break
+	 * any existing ties and avoid incorrect bounds propagation.
+	 */
+	if (need_bswap || insn->imm == 16 || insn->imm == 32)
+		dst_reg->id = 0;
+
 	if (need_bswap) {
 		if (insn->imm == 16)
 			dst_reg->var_off = tnum_bswap16(dst_reg->var_off);
@@ -15992,7 +15999,7 @@ static int maybe_fork_scalars(struct bpf_verifier_env *env, struct bpf_insn *ins
 	else
 		return 0;
 
-	branch = push_stack(env, env->insn_idx + 1, env->insn_idx, false);
+	branch = push_stack(env, env->insn_idx, env->insn_idx, false);
 	if (IS_ERR(branch))
 		return PTR_ERR(branch);
 
@@ -17408,6 +17415,12 @@ static void sync_linked_regs(struct bpf_verifier_env *env, struct bpf_verifier_s
 			continue;
 		if ((reg->id & ~BPF_ADD_CONST) != (known_reg->id & ~BPF_ADD_CONST))
 			continue;
+		/*
+		 * Skip mixed 32/64-bit links: the delta relationship doesn't
+		 * hold across different ALU widths.
+		 */
+		if (((reg->id ^ known_reg->id) & BPF_ADD_CONST) == BPF_ADD_CONST)
+			continue;
 		if ((!(reg->id & BPF_ADD_CONST) && !(known_reg->id & BPF_ADD_CONST)) ||
 		    reg->off == known_reg->off) {
 			s32 saved_subreg_def = reg->subreg_def;
@@ -17435,7 +17448,7 @@ static void sync_linked_regs(struct bpf_verifier_env *env, struct bpf_verifier_s
 			scalar32_min_max_add(reg, &fake_reg);
 			scalar_min_max_add(reg, &fake_reg);
 			reg->var_off = tnum_add(reg->var_off, fake_reg.var_off);
-			if (known_reg->id & BPF_ADD_CONST32)
+			if ((reg->id | known_reg->id) & BPF_ADD_CONST32)
 				zext_32_to_64(reg);
 			reg_bounds_sync(reg);
 		}
@@ -19863,11 +19876,14 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold,
 		 * Also verify that new value satisfies old value range knowledge.
 		 */
 
-		/* ADD_CONST mismatch: different linking semantics */
-		if ((rold->id & BPF_ADD_CONST) && !(rcur->id & BPF_ADD_CONST))
-			return false;
-
-		if (rold->id && !(rold->id & BPF_ADD_CONST) && (rcur->id & BPF_ADD_CONST))
+		/*
+		 * ADD_CONST flags must match exactly: BPF_ADD_CONST32 and
+		 * BPF_ADD_CONST64 have different linking semantics in
+		 * sync_linked_regs() (alu32 zero-extends, alu64 does not),
+		 * so pruning across different flag types is unsafe.
+		 */
+		if (rold->id &&
+		    (rold->id & BPF_ADD_CONST) != (rcur->id & BPF_ADD_CONST))
 			return false;
 
 		/* Both have offset linkage: offsets must match */
@@ -20904,7 +20920,8 @@ static int process_bpf_exit_full(struct bpf_verifier_env *env,
 	 * state when it exits.
 	 */
 	int err = check_resource_leak(env, exception_exit,
-				      !env->cur_state->curframe,
+				      exception_exit || !env->cur_state->curframe,
+				      exception_exit ? "bpf_throw" :
 				      "BPF_EXIT instruction in main prog");
 	if (err)
 		return err;