double free() in error path; from Eusgor via GHPR333

diff --git a/usr.bin/ssh/sshsig.c b/usr.bin/ssh/sshsig.c
index 56cd59a..bdfb3b4 100644 (file)
--- a/usr.bin/ssh/sshsig.c
+++ b/usr.bin/ssh/sshsig.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshsig.c,v 1.29 2022/03/30 04:27:51 djm Exp $ */
+/* $OpenBSD: sshsig.c,v 1.30 2022/08/19 03:06:30 djm Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -489,7 +489,7 @@ hash_file(int fd, const char *hashalg, struct sshbuf **bp)
 {
        char *hex, rbuf[8192], hash[SSH_DIGEST_MAX_LENGTH];
        ssize_t n, total = 0;
-       struct ssh_digest_ctx *ctx;
+       struct ssh_digest_ctx *ctx = NULL;
        int alg, oerrno, r = SSH_ERR_INTERNAL_ERROR;
        struct sshbuf *b = NULL;
 
@@ -512,7 +512,6 @@ hash_file(int fd, const char *hashalg, struct sshbuf **bp)
                                continue;
                        oerrno = errno;
                        error_f("read: %s", strerror(errno));
-                       ssh_digest_free(ctx);
                        errno = oerrno;
                        r = SSH_ERR_SYSTEM_ERROR;
                        goto out;
@@ -547,9 +546,11 @@ hash_file(int fd, const char *hashalg, struct sshbuf **bp)
        /* success */
        r = 0;
  out:
+       oerrno = errno;
        sshbuf_free(b);
        ssh_digest_free(ctx);
        explicit_bzero(hash, sizeof(hash));
+       errno = oerrno;
        return r;
 }