From: anteater <65555601+nt8r@users.noreply.github.com>
Date: Mon, 29 May 2023 20:59:11 +0000 (+0000)
Subject: dmesg: make kmsg read() buffer big enough for kernel
X-Git-Tag: v2.39.1~47
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=9429cc72b5923ca3380235283b969365723643e5;p=thirdparty%2Futil-linux.git

dmesg: make kmsg read() buffer big enough for kernel

otherwise, if the kernel log has an item longer than 1024B, our read() gives EINVAL and we stop reading kmsg
---

diff --git a/sys-utils/dmesg.c b/sys-utils/dmesg.c
index 45075e50bd..717cc588b2 100644
--- a/sys-utils/dmesg.c
+++ b/sys-utils/dmesg.c
@@ -179,7 +179,13 @@ struct dmesg_control {
 
 	int		kmsg;		/* /dev/kmsg file descriptor */
 	ssize_t		kmsg_first_read;/* initial read() return code */
-	char		kmsg_buf[BUFSIZ];/* buffer to read kmsg data */
+	/*
+	 * the kernel will give EINVAL if we do read() on /proc/kmsg with
+	 * length insufficient for the next message. messages may be up to
+	 * PRINTK_MESSAGE_MAX, which is defined as 2048, so we must be
+	 * able to buffer at least that much in one call
+	 */
+	char		kmsg_buf[2048]; /* buffer to read kmsg data */
 
 	usec_t		since;		/* filter records by time */
 	usec_t		until;		/* filter records by time */