From f64d04c042193183c6dad98944ae2861b998e8b7 Mon Sep 17 00:00:00 2001 From: Michael Holzheu Date: Fri, 11 Sep 2009 10:28:59 +0200 Subject: [S390] s390dbf: Add description for usage of "%s" in sprintf events Using "%s" in sprintf event functions is dangerous. This patch adds a short description for this issue to the s390 debug feature documentation. Signed-off-by: Michael Holzheu Signed-off-by: Martin Schwidefsky --- Documentation/s390/s390dbf.txt | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation/s390') diff --git a/Documentation/s390/s390dbf.txt b/Documentation/s390/s390dbf.txt index 2d10053dd97e..ae66f9b90a25 100644 --- a/Documentation/s390/s390dbf.txt +++ b/Documentation/s390/s390dbf.txt @@ -495,6 +495,13 @@ and for each vararg a long value. So e.g. for a debug entry with a format string plus two varargs one would need to allocate a (3 * sizeof(long)) byte data area in the debug_register() function. +IMPORTANT: Using "%s" in sprintf event functions is dangerous. You can only +use "%s" in the sprintf event functions, if the memory for the passed string is +available as long as the debug feature exists. The reason behind this is that +due to performance considerations only a pointer to the string is stored in +the debug feature. If you log a string that is freed afterwards, you will get +an OOPS when inspecting the debug feature, because then the debug feature will +access the already freed memory. NOTE: If using the sprintf view do NOT use other event/exception functions than the sprintf-event and -exception functions. -- cgit v1.2.3