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authorFrederic Weisbecker <fweisbec@gmail.com>2009-08-10 16:38:36 +0200
committerIngo Molnar <mingo@elte.hu>2009-08-10 16:51:19 +0200
commit1853db0e02ae4088f102b0d8e59e83dc98f93f03 (patch)
tree9fd877538baf1904a31eb5436536954cdced5293
parent304703aba31a87903b8c0db8f5e6890cac2d596d (diff)
downloadconfigs-1853db0e02ae4088f102b0d8e59e83dc98f93f03.tar.gz
perf_counter: Zero dead bytes from ftrace raw samples size alignment
After aligning the ftrace raw samples, there are dead bytes storing random data from the stack. We don't want to leak these to userspace, then zero these out. Before: 0x2de88 [0x50]: event: 9 . . ... raw event: size 80 bytes . 0000: 09 00 00 00 01 00 50 00 d0 c7 00 81 ff ff ff ff ......P........ . 0010: 68 01 00 00 68 01 00 00 2c 00 00 00 00 00 00 00 h...h...,...... . 0020: 2c 00 00 00 2b 00 01 02 68 01 00 00 68 01 00 00 ,...+...h...h.. . 0030: 6b 6f 6e 64 65 6d 61 6e 64 2f 30 00 00 00 00 00 kondemand/0.... . 0040: 68 01 00 00 40 7f 46 81 ff ff ff ff 00 10 1b 7f h...@.F........ ^ ^ ^ ^ Leak After: 0x2d318 [0x50]: event: 9 . . ... raw event: size 80 bytes . 0000: 09 00 00 00 01 00 50 00 d0 c7 00 81 ff ff ff ff ......P........ . 0010: 68 01 00 00 68 01 00 00 68 14 00 00 00 00 00 00 h...h...h...... . 0020: 2c 00 00 00 2b 00 01 02 68 01 00 00 68 01 00 00 ,...+...h...h.. . 0030: 6b 6f 6e 64 65 6d 61 6e 64 2f 30 00 00 00 00 00 kondemand/0.... . 0040: 68 01 00 00 a0 80 46 81 ff ff ff ff 00 00 00 00 h.....F........ ^ ^ ^ ^ Fixed Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Mike Galbraith <efault@gmx.de> LKML-Reference: <1249915116-5210-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Mike Galbraith <efault@gmx.de>
-rw-r--r--include/trace/ftrace.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index a05524fa245..f64fbaae781 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -648,6 +648,9 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
* char raw_data[__entry_size]; <- allocate our sample in the stack
* struct trace_entry *ent;
*
+ * zero dead bytes from alignment to avoid stack leak to userspace:
+ *
+ * *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;
* entry = (struct ftrace_raw_<call> *)raw_data;
* ent = &entry->ent;
* tracing_generic_entry_update(ent, irq_flags, pc);
@@ -698,6 +701,7 @@ static void ftrace_profile_##call(proto) \
char raw_data[__entry_size]; \
struct trace_entry *ent; \
\
+ *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL; \
entry = (struct ftrace_raw_##call *)raw_data; \
ent = &entry->ent; \
tracing_generic_entry_update(ent, irq_flags, pc); \