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

Pull bpf fixes from Alexei Starovoitov:

 - Fix u32/s32 bounds when ranges cross min/max boundary (Eduard
   Zingerman)

 - Fix precision backtracking with linked registers (Eduard Zingerman)

 - Fix linker flags detection for resolve_btfids (Ihor Solodrai)

 - Fix race in update_ftrace_direct_add/del (Jiri Olsa)

 - Fix UAF in bpf_trampoline_link_cgroup_shim (Lang Xu)

* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  resolve_btfids: Fix linker flags detection
  selftests/bpf: add reproducer for spurious precision propagation through calls
  bpf: collect only live registers in linked regs
  Revert "selftests/bpf: Update reg_bound range refinement logic"
  selftests/bpf: test refining u32/s32 bounds when ranges cross min/max boundary
  bpf: Fix u32/s32 bounds when ranges cross min/max boundary
  bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim
  ftrace: Add missing ftrace_lock to update_ftrace_direct_add/del

3 files changed, 37 insertions, 6 deletions

diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 84db9e658e52..f02254a21585 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -1002,10 +1002,8 @@ int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
 	mutex_lock(&tr->mutex);
 
 	shim_link = cgroup_shim_find(tr, bpf_func);
-	if (shim_link) {
+	if (shim_link && !IS_ERR(bpf_link_inc_not_zero(&shim_link->link.link))) {
 		/* Reusing existing shim attached by the other program. */
-		bpf_link_inc(&shim_link->link.link);
-
 		mutex_unlock(&tr->mutex);
 		bpf_trampoline_put(tr); /* bpf_trampoline_get above */
 		return 0;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 8db79e593156..159b25f8269d 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2511,6 +2511,30 @@ static void __reg32_deduce_bounds(struct bpf_reg_state *reg)
 	if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) {
 		reg->u32_min_value = max_t(u32, reg->s32_min_value, reg->u32_min_value);
 		reg->u32_max_value = min_t(u32, reg->s32_max_value, reg->u32_max_value);
+	} else {
+		if (reg->u32_max_value < (u32)reg->s32_min_value) {
+			/* See __reg64_deduce_bounds() for detailed explanation.
+			 * Refine ranges in the following situation:
+			 *
+			 * 0                                                   U32_MAX
+			 * |  [xxxxxxxxxxxxxx u32 range xxxxxxxxxxxxxx]              |
+			 * |----------------------------|----------------------------|
+			 * |xxxxx s32 range xxxxxxxxx]                       [xxxxxxx|
+			 * 0                     S32_MAX S32_MIN                    -1
+			 */
+			reg->s32_min_value = (s32)reg->u32_min_value;
+			reg->u32_max_value = min_t(u32, reg->u32_max_value, reg->s32_max_value);
+		} else if ((u32)reg->s32_max_value < reg->u32_min_value) {
+			/*
+			 * 0                                                   U32_MAX
+			 * |              [xxxxxxxxxxxxxx u32 range xxxxxxxxxxxxxx]  |
+			 * |----------------------------|----------------------------|
+			 * |xxxxxxxxx]                       [xxxxxxxxxxxx s32 range |
+			 * 0                     S32_MAX S32_MIN                    -1
+			 */
+			reg->s32_max_value = (s32)reg->u32_max_value;
+			reg->u32_min_value = max_t(u32, reg->u32_min_value, reg->s32_min_value);
+		}
 	}
 }
 
@@ -17335,17 +17359,24 @@ static void __collect_linked_regs(struct linked_regs *reg_set, struct bpf_reg_st
  * in verifier state, save R in linked_regs if R->id == id.
  * If there are too many Rs sharing same id, reset id for leftover Rs.
  */
-static void collect_linked_regs(struct bpf_verifier_state *vstate, u32 id,
+static void collect_linked_regs(struct bpf_verifier_env *env,
+				struct bpf_verifier_state *vstate,
+				u32 id,
 				struct linked_regs *linked_regs)
 {
+	struct bpf_insn_aux_data *aux = env->insn_aux_data;
 	struct bpf_func_state *func;
 	struct bpf_reg_state *reg;
+	u16 live_regs;
 	int i, j;
 
 	id = id & ~BPF_ADD_CONST;
 	for (i = vstate->curframe; i >= 0; i--) {
+		live_regs = aux[frame_insn_idx(vstate, i)].live_regs_before;
 		func = vstate->frame[i];
 		for (j = 0; j < BPF_REG_FP; j++) {
+			if (!(live_regs & BIT(j)))
+				continue;
 			reg = &func->regs[j];
 			__collect_linked_regs(linked_regs, reg, id, i, j, true);
 		}
@@ -17560,9 +17591,9 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
 	 * if parent state is created.
 	 */
 	if (BPF_SRC(insn->code) == BPF_X && src_reg->type == SCALAR_VALUE && src_reg->id)
-		collect_linked_regs(this_branch, src_reg->id, &linked_regs);
+		collect_linked_regs(env, this_branch, src_reg->id, &linked_regs);
 	if (dst_reg->type == SCALAR_VALUE && dst_reg->id)
-		collect_linked_regs(this_branch, dst_reg->id, &linked_regs);
+		collect_linked_regs(env, this_branch, dst_reg->id, &linked_regs);
 	if (linked_regs.cnt > 1) {
 		err = push_jmp_history(env, this_branch, 0, linked_regs_pack(&linked_regs));
 		if (err)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 2f72af0357e5..8df69e702706 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6404,6 +6404,7 @@ int update_ftrace_direct_add(struct ftrace_ops *ops, struct ftrace_hash *hash)
 			new_filter_hash = old_filter_hash;
 		}
 	} else {
+		guard(mutex)(&ftrace_lock);
 		err = ftrace_update_ops(ops, new_filter_hash, EMPTY_HASH);
 		/*
 		 * new_filter_hash is dup-ed, so we need to release it anyway,
@@ -6530,6 +6531,7 @@ int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash)
 			ops->func_hash->filter_hash = NULL;
 		}
 	} else {
+		guard(mutex)(&ftrace_lock);
 		err = ftrace_update_ops(ops, new_filter_hash, EMPTY_HASH);
 		/*
 		 * new_filter_hash is dup-ed, so we need to release it anyway,