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From: David Gibson <david@gibson.dropbear.id.au>
To: passt-dev@passt.top, Stefano Brivio <sbrivio@redhat.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Subject: [PATCH 1/5] util: Be more defensive about buffer overruns in read_file()
Date: Mon,  5 Jan 2026 18:53:33 +1100	[thread overview]
Message-ID: <20260105075337.1724962-2-david@gibson.dropbear.id.au> (raw)
In-Reply-To: <20260105075337.1724962-1-david@gibson.dropbear.id.au>

clang-21.1.7 complains about read_file(), thinking that total_read might
come to exceed buf_size, leading to an out of bounds access at the end of
the function.  In fact, the semantics of read()'s return mean this can't
ever happen.  But we already have to check for the total_read == buf_size
case, so it's basically free to change it to >= and suppress the error.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/util.c b/util.c
index 27303950..a48f727c 100644
--- a/util.c
+++ b/util.c
@@ -715,7 +715,7 @@ static ssize_t read_file(const char *path, char *buf, size_t buf_size)
 
 	close(fd);
 
-	if (total_read == buf_size) {
+	if (total_read >= buf_size) {
 		buf[buf_size - 1] = '\0';
 		return -ENOBUFS;
 	}
-- 
2.52.0


  reply	other threads:[~2026-01-05  7:53 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-01-05  7:53 [PATCH 0/5] Fixes for Fedora 43 (or other bitrot) David Gibson
2026-01-05  7:53 ` David Gibson [this message]
2026-01-06 13:37   ` [PATCH 1/5] util: Be more defensive about buffer overruns in read_file() Laurent Vivier
2026-01-05  7:53 ` [PATCH 2/5] migrate: Don't use terminator element for versions[] array David Gibson
2026-01-06 13:43   ` Laurent Vivier
2026-01-06 13:47   ` Laurent Vivier
2026-01-07  0:10     ` David Gibson
2026-01-05  7:53 ` [PATCH 3/5] treewide: Don't rely on terminator records in ip[46].dns arrays David Gibson
2026-01-06 13:53   ` Laurent Vivier
2026-01-07  0:11     ` David Gibson
2026-01-05  7:53 ` [PATCH 4/5] test: Handle Operating System Command escapes in terminal output David Gibson
2026-01-06 14:07   ` Laurent Vivier
2026-01-05  7:53 ` [PATCH 5/5] test: Include sshd-auth in mbuto guest image David Gibson
2026-01-06 14:11   ` Laurent Vivier

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