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authorAndreas Ziegler <andreas.ziegler@fau.de>2019-02-06 20:00:13 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-02-20 10:29:13 +0100
commitebf5838d6da6a525c78ed55b3ee54c1a4e868d67 (patch)
parent4bbf187b4297f34b8cc3dca5cb2cb03c9343fd29 (diff)
tracing: probeevent: Correctly update remaining space in dynamic area
commit f6675872db57305fa957021efc788f9983ed3b67 upstream. Commit 9178412ddf5a ("tracing: probeevent: Return consumed bytes of dynamic area") improved the string fetching mechanism by returning the number of required bytes after copying the argument to the dynamic area. However, this return value is now only used to increment the pointer inside the dynamic area but misses updating the 'maxlen' variable which indicates the remaining space in the dynamic area. This means that fetch_store_string() always reads the *total* size of the dynamic area from the data_loc pointer instead of the *remaining* size (and passes it along to strncpy_from_{user,unsafe}) even if we're already about to copy data into the middle of the dynamic area. Link: http://lkml.kernel.org/r/20190206190013.16405-1-andreas.ziegler@fau.de Cc: Ingo Molnar <mingo@redhat.com> Cc: stable@vger.kernel.org Fixes: 9178412ddf5a ("tracing: probeevent: Return consumed bytes of dynamic area") Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Andreas Ziegler <andreas.ziegler@fau.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h
index 5c56afc17cf8..4737bb8c07a3 100644
--- a/kernel/trace/trace_probe_tmpl.h
+++ b/kernel/trace/trace_probe_tmpl.h
@@ -180,10 +180,12 @@ store_trace_args(void *data, struct trace_probe *tp, struct pt_regs *regs,
if (unlikely(arg->dynamic))
*dl = make_data_loc(maxlen, dyndata - base);
ret = process_fetch_insn(arg->code, regs, dl, base);
- if (unlikely(ret < 0 && arg->dynamic))
+ if (unlikely(ret < 0 && arg->dynamic)) {
*dl = make_data_loc(0, dyndata - base);
- else
+ } else {
dyndata += ret;
+ maxlen -= ret;
+ }