lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-Id: <1354813571-11253-2-git-send-email-schnhrr@cs.tu-berlin.de> Date: Thu, 6 Dec 2012 18:05:58 +0100 From: Jan H. Schönherr <schnhrr@...tu-berlin.de> To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Kay Sievers <kay@...y.org> Cc: linux-kernel@...r.kernel.org, Joe Perches <joe@...ches.com>, Andrew Morton <akpm@...ux-foundation.org>, Stephen Rothwell <sfr@...b.auug.org.au>, Jan H. Schönherr <schnhrr@...tu-berlin.de> Subject: [PATCH v2 01/14] printk: drop ambiguous LOG_CONT flag The meaning of LOG_CONT is unclear, i. e., whether a message is a starting, ending, or middle fragment. Unfortunately, this cannot be inferred from the LOG_PREFIX and LOG_NEWLINE flags, as they are not always kept. Furthermore, in some cases LOG_CONT is set, although it is unknown if there will be a continuation. This leads to wrongly concatenated output. Fix this by dropping LOG_CONT and rely on LOG_PREFIX and LOG_NEWLINE to distinguish the type of fragment. That is, if LOG_PREFIX is set, this fragment does not continue the previous fragment. And if LOG_NEWLINE is set, this fragment is not continued by the next fragment. (Unfortunately, we still have to look at the previous fragment to catch the case of an unset LOG_PREFIX on this fragment, but a set LOG_NEWLINE on the previous fragment -- and vice versa) Tested-by: Kay Sievers <kay@...y.org> Signed-off-by: Jan H. Schönherr <schnhrr@...tu-berlin.de> --- v2: - minor commit message clarification v1b: - fixed check for flushed buffer - minor code adjustment - coding style fixes --- kernel/printk.c | 58 ++++++++++++++++++++++++++++++++------------------------- 1 file changed, 33 insertions(+), 25 deletions(-) diff --git a/kernel/printk.c b/kernel/printk.c index 2d607f4..857ff7c 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -197,7 +197,6 @@ enum log_flags { LOG_NOCONS = 1, /* already flushed, do not print to console */ LOG_NEWLINE = 2, /* text ended with a newline */ LOG_PREFIX = 4, /* text started with a prefix */ - LOG_CONT = 8, /* text is a fragment of a continuation line */ }; struct log { @@ -481,10 +480,9 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf, * better readable output. 'c' in the record flags mark the first * fragment of a line, '+' the following. */ - if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT)) + if (!(msg->flags & LOG_NEWLINE) && msg->flags & LOG_PREFIX) cont = 'c'; - else if ((msg->flags & LOG_CONT) || - ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))) + else if (!(user->prev & LOG_NEWLINE) && !(msg->flags & LOG_PREFIX)) cont = '+'; len = sprintf(user->buf, "%u,%llu,%llu,%c;", @@ -887,15 +885,16 @@ static size_t msg_print_text(const struct log *msg, enum log_flags prev, bool newline = true; size_t len = 0; - if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)) + if (!(prev & LOG_NEWLINE) && !(msg->flags & LOG_PREFIX)) prefix = false; - if (msg->flags & LOG_CONT) { - if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE)) - prefix = false; + if (!(msg->flags & LOG_NEWLINE)) + newline = false; - if (!(msg->flags & LOG_NEWLINE)) - newline = false; + if (!(prev & LOG_NEWLINE) && prefix) { + if (buf) + buf[len] = '\n'; + len++; } do { @@ -1400,35 +1399,36 @@ static void cont_flush(enum log_flags flags) if (cont.len == 0) return; + cont.flags |= flags; if (cont.cons) { /* * If a fragment of this line was directly flushed to the * console; wait for the console to pick up the rest of the * line. LOG_NOCONS suppresses a duplicated output. */ - log_store(cont.facility, cont.level, flags | LOG_NOCONS, + log_store(cont.facility, cont.level, cont.flags | LOG_NOCONS, cont.ts_nsec, NULL, 0, cont.buf, cont.len); - cont.flags = flags; cont.flushed = true; } else { /* * If no fragment of this line ever reached the console, * just submit it to the store and free the buffer. */ - log_store(cont.facility, cont.level, flags, 0, + log_store(cont.facility, cont.level, cont.flags, 0, NULL, 0, cont.buf, cont.len); cont.len = 0; } } -static bool cont_add(int facility, int level, const char *text, size_t len) +static bool cont_add(int facility, int level, enum log_flags flags, + const char *text, size_t len) { if (cont.len && cont.flushed) return false; if (cont.len + len > sizeof(cont.buf)) { /* the line gets too long, split it up in separate records */ - cont_flush(LOG_CONT); + cont_flush(0); return false; } @@ -1437,7 +1437,7 @@ static bool cont_add(int facility, int level, const char *text, size_t len) cont.level = level; cont.owner = current; cont.ts_nsec = local_clock(); - cont.flags = 0; + cont.flags = flags; cont.cons = 0; cont.flushed = false; } @@ -1446,7 +1446,7 @@ static bool cont_add(int facility, int level, const char *text, size_t len) cont.len += len; if (cont.len > (sizeof(cont.buf) * 80) / 100) - cont_flush(LOG_CONT); + cont_flush(0); return true; } @@ -1456,8 +1456,11 @@ static size_t cont_print_text(char *text, size_t size) size_t textlen = 0; size_t len; - if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) { - textlen += print_time(cont.ts_nsec, text); + if (cont.cons == 0 && (console_prev & LOG_NEWLINE || + cont.flags & LOG_PREFIX)) { + if (!(console_prev & LOG_NEWLINE)) + text[textlen++] = '\n'; + textlen += print_time(cont.ts_nsec, text + textlen); size -= textlen; } @@ -1575,12 +1578,16 @@ asmlinkage int vprintk_emit(int facility, int level, * Flush the conflicting buffer. An earlier newline was missing, * or another task also prints continuation lines. */ - if (cont.len && (lflags & LOG_PREFIX || cont.owner != current)) - cont_flush(LOG_NEWLINE); + if (cont.len && !cont.flushed) { + if (cont.owner != current) + lflags |= LOG_PREFIX; + if (lflags & LOG_PREFIX) + cont_flush(LOG_NEWLINE); + } /* buffer line if possible, otherwise store it right away */ - if (!cont_add(facility, level, text, text_len)) - log_store(facility, level, lflags | LOG_CONT, 0, + if (!cont_add(facility, level, lflags, text, text_len)) + log_store(facility, level, lflags, 0, dict, dictlen, text, text_len); } else { bool stored = false; @@ -1591,9 +1598,10 @@ asmlinkage int vprintk_emit(int facility, int level, * there was a race with interrupts (prefix == true) then just * flush it out and store this line separately. */ - if (cont.len && cont.owner == current) { + if (cont.len && !cont.flushed && cont.owner == current) { if (!(lflags & LOG_PREFIX)) - stored = cont_add(facility, level, text, text_len); + stored = cont_add(facility, level, lflags, + text, text_len); cont_flush(LOG_NEWLINE); } -- 1.8.0.1.20.g7c65b2e.dirty -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists