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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>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kay Sievers 2012-07-16 18:35:29 -07:00 committed by Greg Kroah-Hartman
parent 28a78e46f0
commit 7049825318
1 changed files with 19 additions and 14 deletions
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29
kernel/printk.c
View File

@ -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)
@ -907,7 +908,7 @@ static int syslog_print(char __user *buf, int size)
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, int size)
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 *buf, int size, bool clear)
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 *buf, int size, bool clear)
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 level, const char *text, size_t len)
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, int level,
* 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, int level,
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)
@ -1634,6 +1638,7 @@ EXPORT_SYMBOL(printk);
#else
#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;