diff options
| -rw-r--r-- | Documentation/s390/s390dbf.txt | 7 | ||||
| -rw-r--r-- | arch/s390/include/asm/debug.h | 9 |
2 files changed, 15 insertions, 1 deletions
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. diff --git a/arch/s390/include/asm/debug.h b/arch/s390/include/asm/debug.h index 31ed5686a968..18124b75a7ab 100644 --- a/arch/s390/include/asm/debug.h +++ b/arch/s390/include/asm/debug.h @@ -167,6 +167,10 @@ debug_text_event(debug_info_t* id, int level, const char* txt) return debug_event_common(id,level,txt,strlen(txt)); } +/* + * IMPORTANT: Use "%s" in sprintf format strings with care! Only pointers are + * stored in the s390dbf. See Documentation/s390/s390dbf.txt for more details! + */ extern debug_entry_t * debug_sprintf_event(debug_info_t* id,int level,char *string,...) __attribute__ ((format(printf, 3, 4))); @@ -206,7 +210,10 @@ debug_text_exception(debug_info_t* id, int level, const char* txt) return debug_exception_common(id,level,txt,strlen(txt)); } - +/* + * IMPORTANT: Use "%s" in sprintf format strings with care! Only pointers are + * stored in the s390dbf. See Documentation/s390/s390dbf.txt for more details! + */ extern debug_entry_t * debug_sprintf_exception(debug_info_t* id,int level,char *string,...) __attribute__ ((format(printf, 3, 4))); |