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From: Kay Sievers <kay@vrfy.org>
Subject: kmsg - properly print over-long continuation lines
Reserve PREFIX_MAX bytes in the LOG_LINE_MAX line when buffering a
continuation line, to be able to properly prefix the LOG_LINE_MAX
line with the syslog prefix and timestamp when printing it.
Reported-By: Dave Jones <davej@redhat.com>
Signed-off-by: Kay Sievers <kay@vrfy.org>
---
kernel/printk.c | 33 +++++++++++++++++++--------------
1 file changed, 19 insertions(+), 14 deletions(-)
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -235,7 +235,8 @@ static u32 log_next_idx;
static u64 clear_seq;
static u32 clear_idx;
-#define LOG_LINE_MAX 1024
+#define PREFIX_MAX 32
+#define LOG_LINE_MAX 1024 - PREFIX_MAX
/* record buffer */
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
@@ -876,7 +877,7 @@ static size_t msg_print_text(const struc
if (buf) {
if (print_prefix(msg, syslog, NULL) +
- text_len + 1>= size - len)
+ text_len + 1 >= size - len)
break;
if (prefix)
@@ -907,7 +908,7 @@ static int syslog_print(char __user *buf
struct log *msg;
int len = 0;
- text = kmalloc(LOG_LINE_MAX, GFP_KERNEL);
+ text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
@@ -930,7 +931,8 @@ static int syslog_print(char __user *buf
skip = syslog_partial;
msg = log_from_idx(syslog_idx);
- n = msg_print_text(msg, syslog_prev, true, text, LOG_LINE_MAX);
+ n = msg_print_text(msg, syslog_prev, true, text,
+ LOG_LINE_MAX + PREFIX_MAX);
if (n - syslog_partial <= size) {
/* message fits into buffer, move forward */
syslog_idx = log_next(syslog_idx);
@@ -969,7 +971,7 @@ static int syslog_print_all(char __user
char *text;
int len = 0;
- text = kmalloc(LOG_LINE_MAX, GFP_KERNEL);
+ text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
@@ -1022,7 +1024,8 @@ static int syslog_print_all(char __user
struct log *msg = log_from_idx(idx);
int textlen;
- textlen = msg_print_text(msg, prev, true, text, LOG_LINE_MAX);
+ textlen = msg_print_text(msg, prev, true, text,
+ LOG_LINE_MAX + PREFIX_MAX);
if (textlen < 0) {
len = textlen;
break;
@@ -1367,15 +1370,15 @@ static struct cont {
bool flushed:1; /* buffer sealed and committed */
} cont;
-static void cont_flush(void)
+static void cont_flush(enum log_flags flags)
{
if (cont.flushed)
return;
if (cont.len == 0)
return;
- log_store(cont.facility, cont.level, LOG_NOCONS, cont.ts_nsec,
- NULL, 0, cont.buf, cont.len);
+ log_store(cont.facility, cont.level, LOG_NOCONS | flags,
+ cont.ts_nsec, NULL, 0, cont.buf, cont.len);
cont.flushed = true;
}
@@ -1386,7 +1389,8 @@ static bool cont_add(int facility, int l
return false;
if (cont.len + len > sizeof(cont.buf)) {
- cont_flush();
+ /* the line gets too long, split it up in separate records */
+ cont_flush(LOG_CONT);
return false;
}
@@ -1522,7 +1526,7 @@ asmlinkage int vprintk_emit(int facility
* or another task also prints continuation lines.
*/
if (cont.len && (lflags & LOG_PREFIX || cont.owner != current))
- cont_flush();
+ cont_flush(0);
/* buffer line if possible, otherwise store it right away */
if (!cont_add(facility, level, text, text_len))
@@ -1540,7 +1544,7 @@ asmlinkage int vprintk_emit(int facility
if (cont.len && cont.owner == current) {
if (!(lflags & LOG_PREFIX))
stored = cont_add(facility, level, text, text_len);
- cont_flush();
+ cont_flush(0);
}
if (!stored)
@@ -1633,7 +1637,8 @@ EXPORT_SYMBOL(printk);
#else
-#define LOG_LINE_MAX 0
+#define LOG_LINE_MAX 0
+#define PREFIX_MAX 0
static struct cont {
size_t len;
size_t cons;
@@ -1938,7 +1943,7 @@ static enum log_flags console_prev;
*/
void console_unlock(void)
{
- static char text[LOG_LINE_MAX];
+ static char text[LOG_LINE_MAX + PREFIX_MAX];
static u64 seen_seq;
unsigned long flags;
bool wake_klogd = false;
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