bpf: Take return from set_memory_ro() into account with bpf_prog_lock…

…_ro() set_memory_ro() can fail, leaving memory unprotected. Check its return and take it into account as an error. Link: KSPP/linux#7 Signed-off-by: Christophe Leroy <[email protected]> Cc: [email protected] <[email protected]> Reviewed-by: Kees Cook <[email protected]>
kernel-patches · Mar 1, 2024 · 19fa577 · 19fa577
1 parent a1bb1c9
commit 19fa577
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Showing 3 changed files with 9 additions and 4 deletions.
diff --git a/include/linux/filter.h b/include/linux/filter.h
@@ -884,14 +884,15 @@ bpf_ctx_narrow_access_offset(u32 off, u32 size, u32 size_default)
 
 #define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0]))
 
-static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
+static inline int __must_check bpf_prog_lock_ro(struct bpf_prog *fp)
 {
 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
 	if (!fp->jited) {
 		set_vm_flush_reset_perms(fp);
-		set_memory_ro((unsigned long)fp, fp->pages);
+		return set_memory_ro((unsigned long)fp, fp->pages);
 	}
 #endif
+	return 0;
 }
 
 static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
@@ -2392,7 +2392,9 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
 	}
 
 finalize:
-	bpf_prog_lock_ro(fp);
+	*err = bpf_prog_lock_ro(fp);
+	if (*err)
+		return fp;
 
 	/* The tail call compatibility check can only be done at
 	 * this late stage as we need to determine, if we deal

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
@@ -19096,7 +19096,9 @@ static int jit_subprogs(struct bpf_verifier_env *env)
 	 * bpf_prog_load will add the kallsyms for the main program.
 	 */
 	for (i = 1; i < env->subprog_cnt; i++) {
-		bpf_prog_lock_ro(func[i]);
+		err = bpf_prog_lock_ro(func[i]);
+		if (err)
+			goto out_free;
 		bpf_prog_kallsyms_add(func[i]);
 	}