Re: [PATCH 00/23] Crypto keys and module signing

[David Howells <dhowells@xxxxxxxxxx>]

Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote:

> PATCH 16/23
> ...
> Should we check ctx.dsize < sizeof(ctx.descbuf) - 4
> in case caller is modified in the future?

Probably.  I'm going to assume that BUG_ON() is a good enough check for the
moment as I assume the prefix will probably be generated at compile time.

David
---
diff --git a/security/keys/crypto/pgp_preload.c b/security/keys/crypto/pgp_preload.c
index 25154e3..ef53902 100644
--- a/security/keys/crypto/pgp_preload.c
+++ b/security/keys/crypto/pgp_preload.c
@@ -35,6 +35,9 @@ static int __init found_pgp_key(struct pgp_parse_context *context,
 		container_of(context, struct preload_pgp_keys_context, pgp);
 	key_ref_t key;
 
+	if (ctx->key_n > 999)
+		return 0; /* Don't overrun descbuf */
+
 	sprintf(ctx->descbuf + ctx->dsize, "%d", ctx->key_n++);
 
 	key = key_create_or_update(ctx->keyring, "crypto", ctx->descbuf,
@@ -84,6 +87,7 @@ int __init preload_pgp_keys(const u8 *pgpdata, size_t pgpdatalen,
 	ctx.keyring = make_key_ref(keyring, 1);
 	ctx.key_n = 0;
 	ctx.dsize = strlen(descprefix);
+	BUG_ON(ctx.dsize > sizeof(ctx.descbuf) - 4);
 	strcpy(ctx.descbuf, descprefix);
 
 	return pgp_parse_packets(pgpdata, pgpdatalen, &ctx.pgp);
--
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