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Subject[RFC PATCH] kernel/panic: Filter out a potential trailing newline
Date
From: Borislav Petkov <bp@suse.de>

If a call to panic() terminates the string with a \n, the result puts
the closing brace ']---' on a newline because panic() itself adds \n
too.

Now, if one goes and removes the newline chars from all panic()
invocations - and the stats right now look like this:

~300 calls with an \n
~500 calls without a \n

one is destined to a neverending game of whack-a-mole because the usual
thing to do is add a newline at the end of a string a function is
supposed to print.

Therefore, simply zap any \n at the end of the panic string to avoid
touching so many places in the kernel.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: x86@kernel.org
---
kernel/panic.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/panic.c b/kernel/panic.c
index 8b2e002d52eb..5776d2879650 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -136,7 +136,7 @@ void panic(const char *fmt, ...)
{
static char buf[1024];
va_list args;
- long i, i_next = 0;
+ long i, i_next = 0, len;
int state = 0;
int old_cpu, this_cpu;
bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
@@ -173,8 +173,12 @@ void panic(const char *fmt, ...)
console_verbose();
bust_spinlocks(1);
va_start(args, fmt);
- vsnprintf(buf, sizeof(buf), fmt, args);
+ len = vscnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
+
+ if (len && buf[len - 1] == '\n')
+ buf[len - 1] = '\0';
+
pr_emerg("Kernel panic - not syncing: %s\n", buf);
#ifdef CONFIG_DEBUG_BUGVERBOSE
/*
--
2.19.0.271.gfe8321ec057f
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