bpf: Take return from set_memory_ro() into account with bpf_prog_lock_ro()

[ Upstream commit 7d2cc63eca0c993c99d18893214abf8f85d566d8 ]

set_memory_ro() can fail, leaving memory unprotected.

Check its return and take it into account as an error.

Link: https://github.com/KSPP/linux/issues/7
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: linux-hardening@vger.kernel.org <linux-hardening@vger.kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Message-ID: <286def78955e04382b227cb3e4b6ba272a7442e3.1709850515.git.christophe.leroy@csgroup.eu>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 219ee7a76874439e9a2ecda7a402a7a9e741e0be..35791b1c61c7d43999243e93528a35b0b47f59a1 100644 (file)
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -887,14 +887,15 @@ 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
index 1ea5ce5bb59933ac4449567c52f1981c8df8a139..9985988845e36da6ec9abdad763c7a7c27357366 100644 (file)
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2403,7 +2403,9 @@ 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
index ab558eea1c9ee5be775884cedda27163af4afb39..d5fca9deac5a16a612de98a0a9ce75c108e72c81 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -19354,10 +19354,14 @@ 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]);
-               bpf_prog_kallsyms_add(func[i]);
+               err = bpf_prog_lock_ro(func[i]);
+               if (err)
+                       goto out_free;
        }
 
+       for (i = 1; i < env->subprog_cnt; i++)
+               bpf_prog_kallsyms_add(func[i]);
+
        /* Last step: make now unused interpreter insns from main
         * prog consistent for later dump requests, so they can
         * later look the same as if they were interpreted only.