mailing list of musl libc
 help / color / mirror / code / Atom feed
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: musl@lists.openwall.com
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: [musl] [PATCH] getentropy: fail if buffer not completely filled
Date: Sat,  9 Apr 2022 02:10:47 +0200	[thread overview]
Message-ID: <20220409001047.234283-1-Jason@zx2c4.com> (raw)

The man page for getentropy says that it either completely succeeds or
completely fails, and indeed this is what glibc does. However, musl has
a condition where it breaks out of the loop early, yet still returns a
success. This patch fixes that by returning a success only if the buffer
is completely filled. While we're at it, prevent an unexpected infinite
loop if the function returns 0, the same way glibc does, just in case.
---
 src/misc/getentropy.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/misc/getentropy.c b/src/misc/getentropy.c
index 651ea95f..5b2fc7a1 100644
--- a/src/misc/getentropy.c
+++ b/src/misc/getentropy.c
@@ -6,7 +6,7 @@
 
 int getentropy(void *buffer, size_t len)
 {
-	int cs, ret = 0;
+	int cs, ret;
 	char *pos = buffer;
 
 	if (len > 256) {
@@ -18,16 +18,19 @@ int getentropy(void *buffer, size_t len)
 
 	while (len) {
 		ret = getrandom(pos, len, 0);
-		if (ret < 0) {
+		if (ret <= 0) {
 			if (errno == EINTR) continue;
 			else break;
 		}
 		pos += ret;
 		len -= ret;
-		ret = 0;
 	}
 
 	pthread_setcancelstate(cs, 0);
 
-	return ret;
+	if (len) {
+		errno = EIO;
+		return -1;
+	}
+	return 0;
 }
-- 
2.35.1


             reply	other threads:[~2022-04-09 11:16 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-09  0:10 Jason A. Donenfeld [this message]
2022-04-09 13:18 ` Rich Felker
2022-04-09 22:50   ` Jason A. Donenfeld
2022-04-09 22:58     ` [musl] [PATCH v2] " Jason A. Donenfeld
2022-04-09 22:58       ` [musl] [PATCH v3] " Jason A. Donenfeld
2022-04-10 15:30       ` [musl] [PATCH v2] " Rich Felker

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220409001047.234283-1-Jason@zx2c4.com \
    --to=jason@zx2c4.com \
    --cc=musl@lists.openwall.com \
    --subject='Re: [musl] [PATCH] getentropy: fail if buffer not completely filled' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Code repositories for project(s) associated with this inbox:

	https://git.vuxu.org/mirror/musl/

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).