[PATCH 15/43] perf trace: Check if the 'fd' is negative when mapping it to pathname

From: Arnaldo Carvalho de Melo
Date: Thu Feb 14 2019 - 19:46:59 EST

From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

We were crashing when processing a negative fd:

Program received signal SIGSEGV, Segmentation fault.
0x0000000000609bbf in syscall_arg__scnprintf_ioctl_cmd (bf=0x1172eca "", size=2038, arg=0x7fffffff8360) at trace/beauty/ioctl.c:182
182 if (file->dev_maj == USB_DEVICE_MAJOR)
Missing separate debuginfos, use: dnf debuginfo-install bzip2-libs-1.0.6-28.fc29.x86_64 elfutils-libelf-0.174-5.fc29.x86_64 elfutils-libs-0.174-5.fc29.x86_64 glib2-2.58.3-1.fc29.x86_64 libbabeltrace-1.5.6-1.fc29.x86_64 libunwind-1.2.1-6.fc29.x86_64 libuuid-2.32.1-1.fc29.x86_64 libxcrypt-4.4.3-2.fc29.x86_64 numactl-libs-2.0.12-1.fc29.x86_64 openssl-libs-1.1.1a-1.fc29.x86_64 pcre-8.42-6.fc29.x86_64 perl-libs-5.28.1-427.fc29.x86_64 popt-1.16-15.fc29.x86_64 python2-libs-2.7.15-11.fc29.x86_64 slang-2.3.2-4.fc29.x86_64 xz-libs-5.2.4-3.fc29.x86_64
(gdb) bt
#0 0x0000000000609bbf in syscall_arg__scnprintf_ioctl_cmd (bf=0x1172eca "", size=2038, arg=0x7fffffff8360) at trace/beauty/ioctl.c:182
#1 0x000000000048e295 in syscall__scnprintf_val (sc=0x123b500, bf=0x1172eca "", size=2038, arg=0x7fffffff8360, val=21519)
at builtin-trace.c:1594
#2 0x000000000048e60d in syscall__scnprintf_args (sc=0x123b500, bf=0x1172ec6 "-1, ", size=2042, args=0x7ffff6a7c034 "\377\377\377\377",
augmented_args=0x7ffff6a7c064, augmented_args_size=4, trace=0x7fffffffa8d0, thread=0x1175cd0) at builtin-trace.c:1661
#3 0x000000000048f04e in trace__sys_enter (trace=0x7fffffffa8d0, evsel=0xb260b0, event=0x7ffff6a7bfe8, sample=0x7fffffff84f0)
at builtin-trace.c:1880
#4 0x00000000004915a4 in trace__handle_event (trace=0x7fffffffa8d0, event=0x7ffff6a7bfe8, sample=0x7fffffff84f0) at builtin-trace.c:2590
#5 0x0000000000491eed in __trace__deliver_event (trace=0x7fffffffa8d0, event=0x7ffff6a7bfe8) at builtin-trace.c:2818
#6 0x0000000000492030 in trace__deliver_event (trace=0x7fffffffa8d0, event=0x7ffff6a7bfe8) at builtin-trace.c:2845
#7 0x0000000000492896 in trace__run (trace=0x7fffffffa8d0, argc=0, argv=0x7fffffffdb58) at builtin-trace.c:3040
#8 0x000000000049603a in cmd_trace (argc=0, argv=0x7fffffffdb58) at builtin-trace.c:3952
#9 0x00000000004d5103 in main (argc=1, argv=0x7fffffffdb58) at perf.c:474
(gdb) p fd
$1 = -1
(gdb) p file
$7 = (struct file *) 0xfffffffffffffff0
(gdb) p ((struct thread_trace *)arg->thread)->files.table + fd
$8 = (struct file *) 0xfffffffffffffff0

Check for that and return NULL instead.

This problem was introduced recently, the other codepaths leading to
thread_trace__files_entry() check for negative fds, like thread__fd_path(),
but we need to do it at thread_trace__files_entry() as more users are now
calling it directly.

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Luis ClÃudio GonÃalves <lclaudio@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Fixes: 2d473389f87a ("perf trace beauty: Export function to get the files for a thread")
Link: https://lkml.kernel.org/n/tip-oq7bvaaf07gsd4yqty3107u2@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
tools/perf/builtin-trace.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index b4e420c41831..a9b51f59ab54 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1041,6 +1041,9 @@ static const size_t trace__entry_str_size = 2048;

static struct file *thread_trace__files_entry(struct thread_trace *ttrace, int fd)
+ if (fd < 0)
+ return NULL;
if (fd > ttrace->files.max) {
struct file *nfiles = realloc(ttrace->files.table, (fd + 1) * sizeof(struct file));