From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by passt.top (Postfix, from userid 1000) id 0FD405A0271; Thu, 03 Apr 2025 21:04:43 +0200 (CEST) From: Stefano Brivio To: passt-dev@passt.top Subject: [PATCH] passt-repair: Ensure that read buffer is NULL-terminated Date: Thu, 3 Apr 2025 21:04:43 +0200 Message-ID: <20250403190443.1932107-1-sbrivio@redhat.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID-Hash: AC65TTHNCYGOVZXZBWZ652GO53DRZHAU X-Message-ID-Hash: AC65TTHNCYGOVZXZBWZ652GO53DRZHAU X-MailFrom: sbrivio@passt.top X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: David Gibson X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: After 3d41e4d83895 ("passt-repair: Correct off-by-one error verifying name"), Coverity Scan isn't convinced anymore about the fact that the ev->name used in the snprintf() is NULL-terminated. It comes from a read() call, and read() of course doesn't terminate it, but we already check that the byte at ev->len - 1 is a NULL terminator, so this is actually a false positive. In any case, the logic ensuring that ev->name is NULL-terminated isn't necessarily obvious, and additionally checking that the last byte in the buffer we read is a NULL terminator is harmless, so do that explicitly, even if it's redundant. Signed-off-by: Stefano Brivio --- passt-repair.c | 1 + 1 file changed, 1 insertion(+) diff --git a/passt-repair.c b/passt-repair.c index 440c77a..256a8c9 100644 --- a/passt-repair.c +++ b/passt-repair.c @@ -137,6 +137,7 @@ int main(int argc, char **argv) fprintf(stderr, "inotify read: %i", errno); _exit(1); } + buf[n - 1] = '\0'; if (n < (ssize_t)sizeof(*ev)) { fprintf(stderr, "Short inotify read: %zi", n); -- 2.43.0