Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2024-04-26

We've added 12 non-merge commits during the last 22 day(s) which contain
a total of 14 files changed, 168 insertions(+), 72 deletions(-).

The main changes are:

1) Fix BPF_PROBE_MEM in verifier and JIT to skip loads from vsyscall page,
   from Puranjay Mohan.

2) Fix a crash in XDP with devmap broadcast redirect when the latter map
   is in process of being torn down, from Toke Høiland-Jørgensen.

3) Fix arm64 and riscv64 BPF JITs to properly clear start time for BPF
   program runtime stats, from Xu Kuohai.

4) Fix a sockmap KCSAN-reported data race in sk_psock_skb_ingress_enqueue,
    from Jason Xing.

5) Fix BPF verifier error message in resolve_pseudo_ldimm64,
   from Anton Protopopov.

6) Fix missing DEBUG_INFO_BTF_MODULES Kconfig menu item,
   from Andrii Nakryiko.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  selftests/bpf: Test PROBE_MEM of VSYSCALL_ADDR on x86-64
  bpf, x86: Fix PROBE_MEM runtime load check
  bpf: verifier: prevent userspace memory access
  xdp: use flags field to disambiguate broadcast redirect
  arm32, bpf: Reimplement sign-extension mov instruction
  riscv, bpf: Fix incorrect runtime stats
  bpf, arm64: Fix incorrect runtime stats
  bpf: Fix a verifier verbose message
  bpf, skmsg: Fix NULL pointer dereference in sk_psock_skb_ingress_enqueue
  MAINTAINERS: bpf: Add Lehui and Puranjay as riscv64 reviewers
  MAINTAINERS: Update email address for Puranjay Mohan
  bpf, kconfig: Fix DEBUG_INFO_BTF_MODULES Kconfig definition
====================

Link: https://lore.kernel.org/r/20240426224248.26197-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 31 insertions, 32 deletions

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index df5fac428408..59cbc94b6e69 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1807,36 +1807,41 @@ populate_extable:
 			if (BPF_MODE(insn->code) == BPF_PROBE_MEM ||
 			    BPF_MODE(insn->code) == BPF_PROBE_MEMSX) {
 				/* Conservatively check that src_reg + insn->off is a kernel address:
-				 *   src_reg + insn->off >= TASK_SIZE_MAX + PAGE_SIZE
-				 * src_reg is used as scratch for src_reg += insn->off and restored
-				 * after emit_ldx if necessary
+				 *   src_reg + insn->off > TASK_SIZE_MAX + PAGE_SIZE
+				 *   and
+				 *   src_reg + insn->off < VSYSCALL_ADDR
 				 */
 
-				u64 limit = TASK_SIZE_MAX + PAGE_SIZE;
+				u64 limit = TASK_SIZE_MAX + PAGE_SIZE - VSYSCALL_ADDR;
 				u8 *end_of_jmp;
 
-				/* At end of these emitted checks, insn->off will have been added
-				 * to src_reg, so no need to do relative load with insn->off offset
-				 */
-				insn_off = 0;
+				/* movabsq r10, VSYSCALL_ADDR */
+				emit_mov_imm64(&prog, BPF_REG_AX, (long)VSYSCALL_ADDR >> 32,
+					       (u32)(long)VSYSCALL_ADDR);
 
-				/* movabsq r11, limit */
-				EMIT2(add_1mod(0x48, AUX_REG), add_1reg(0xB8, AUX_REG));
-				EMIT((u32)limit, 4);
-				EMIT(limit >> 32, 4);
+				/* mov src_reg, r11 */
+				EMIT_mov(AUX_REG, src_reg);
 
 				if (insn->off) {
-					/* add src_reg, insn->off */
-					maybe_emit_1mod(&prog, src_reg, true);
-					EMIT2_off32(0x81, add_1reg(0xC0, src_reg), insn->off);
+					/* add r11, insn->off */
+					maybe_emit_1mod(&prog, AUX_REG, true);
+					EMIT2_off32(0x81, add_1reg(0xC0, AUX_REG), insn->off);
 				}
 
-				/* cmp src_reg, r11 */
-				maybe_emit_mod(&prog, src_reg, AUX_REG, true);
-				EMIT2(0x39, add_2reg(0xC0, src_reg, AUX_REG));
+				/* sub r11, r10 */
+				maybe_emit_mod(&prog, AUX_REG, BPF_REG_AX, true);
+				EMIT2(0x29, add_2reg(0xC0, AUX_REG, BPF_REG_AX));
+
+				/* movabsq r10, limit */
+				emit_mov_imm64(&prog, BPF_REG_AX, (long)limit >> 32,
+					       (u32)(long)limit);
+
+				/* cmp r10, r11 */
+				maybe_emit_mod(&prog, AUX_REG, BPF_REG_AX, true);
+				EMIT2(0x39, add_2reg(0xC0, AUX_REG, BPF_REG_AX));
 
-				/* if unsigned '>=', goto load */
-				EMIT2(X86_JAE, 0);
+				/* if unsigned '>', goto load */
+				EMIT2(X86_JA, 0);
 				end_of_jmp = prog;
 
 				/* xor dst_reg, dst_reg */
@@ -1862,18 +1867,6 @@ populate_extable:
 				/* populate jmp_offset for JMP above */
 				start_of_ldx[-1] = prog - start_of_ldx;
 
-				if (insn->off && src_reg != dst_reg) {
-					/* sub src_reg, insn->off
-					 * Restore src_reg after "add src_reg, insn->off" in prev
-					 * if statement. But if src_reg == dst_reg, emit_ldx
-					 * above already clobbered src_reg, so no need to restore.
-					 * If add src_reg, insn->off was unnecessary, no need to
-					 * restore either.
-					 */
-					maybe_emit_1mod(&prog, src_reg, true);
-					EMIT2_off32(0x81, add_1reg(0xE8, src_reg), insn->off);
-				}
-
 				if (!bpf_prog->aux->extable)
 					break;
 
@@ -3473,3 +3466,9 @@ bool bpf_jit_supports_ptr_xchg(void)
 {
 	return true;
 }
+
+/* x86-64 JIT emits its own code to filter user addresses so return 0 here */
+u64 bpf_arch_uaddress_limit(void)
+{
+	return 0;
+}