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authorStefan Hajnoczi <stefanha@redhat.com>2019-03-21 17:08:30 +0000
committerStefan Hajnoczi <stefanha@redhat.com>2019-03-22 15:55:50 +0000
commitfd9858317a3d06c94ad8c1c420e6b5c376f5a92e (patch)
treec87f18f18631f5c5bdcd999cda694e9458dc74e1
parentd97a39d903fe33c45be83ac6943a2f82a3649a11 (diff)
downloadqemu-arm-fd9858317a3d06c94ad8c1c420e6b5c376f5a92e.tar.gz
trace: handle tracefs path truncation
If the tracefs mountpoint has a very long path we may exceed PATH_MAX. This is a system misconfiguration and the user must resolve it so that applications can perform path-based system calls successfully. This issue does not occur on real-world systems since tracefs is mounted on /sys/kernel/debug/tracing/, but the compiler is smart enough to foresee the possibility and warn about the unchecked snprintf(3) return value. This patch fixes the compiler warning. Reported-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Liam Merwick <liam.merwick@oracle.com> Message-id: 20190321170831.6539-2-stefanha@redhat.com Message-Id: <20190321170831.6539-2-stefanha@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-rw-r--r--trace/ftrace.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/trace/ftrace.c b/trace/ftrace.c
index 61692a8682..9749543d9b 100644
--- a/trace/ftrace.c
+++ b/trace/ftrace.c
@@ -53,7 +53,11 @@ bool ftrace_init(void)
}
if (tracefs_found) {
- snprintf(path, PATH_MAX, "%s%s/tracing_on", mount_point, subdir);
+ if (snprintf(path, PATH_MAX, "%s%s/tracing_on", mount_point, subdir)
+ >= sizeof(path)) {
+ fprintf(stderr, "Using tracefs mountpoint would exceed PATH_MAX\n");
+ return false;
+ }
trace_fd = open(path, O_WRONLY);
if (trace_fd < 0) {
if (errno == EACCES) {
@@ -72,7 +76,11 @@ bool ftrace_init(void)
}
close(trace_fd);
}
- snprintf(path, PATH_MAX, "%s%s/trace_marker", mount_point, subdir);
+ if (snprintf(path, PATH_MAX, "%s%s/trace_marker", mount_point, subdir)
+ >= sizeof(path)) {
+ fprintf(stderr, "Using tracefs mountpoint would exceed PATH_MAX\n");
+ return false;
+ }
trace_marker_fd = open(path, O_WRONLY);
if (trace_marker_fd < 0) {
perror("Could not open ftrace 'trace_marker' file");