From 70498253186586e5dca7bc3ebd3415203b059fbc Mon Sep 17 00:00:00 2001 From: Kay Sievers Date: Mon, 16 Jul 2012 18:35:29 -0700 Subject: [PATCH] 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 Signed-off-by: Kay Sievers Cc: stable Signed-off-by: Greg Kroah-Hartman --- kernel/printk.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) diff --git a/kernel/printk.c b/kernel/printk.c index 177fa49357a5..d87ca5c6a989 100644 --- 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 struct log *msg, enum log_flags prev, 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, 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) @@ -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; -- 2.39.2