When running perf in a namespace, workload from other namespaces
are accounted to PID 0. During thread initialization for PID 0,
nsinfo__new(PID 0) returns NULL.
Later, a missing NULL pointer check in nsinfo__copy() that is
called from map__new() to handle vdso maps might cause a
segmentation fault.
For example, the segmentation fault can be seen when running
perf top in a namespace created with:
unshare --fork --pid --mount-proc /bin/bash
while running some workload, e.g., find /, in a different
namespace. The resulting stack trace might look like:
(gdb)
#0 nsinfo__copy (nsi=0x0) at util/namespaces.c:143
#1 0x000000010010fe3a in map__new (machine=<optimized out>, start=132816, len=<optimized out>, pgoff=<optimized out>, d_maj=<optimized out>, d_min=0, ino=0,
ino_gen=0, prot=5, flags=4098, filename=0x3fffcb01180 "[vdso]", type=MAP__FUNCTION, thread=0x101c3c050) at util/map.c:192
#2 0x000000010010e1a4 in machine__process_mmap2_event (machine=0x101c3bab8, event=0x3fffcb01138, sample=<optimized out>) at util/machine.c:1397
#3 0x00000001000659d8 in perf_top__mmap_read_idx (top=top@entry=0x3ffffff91d0, idx=idx@entry=0) at builtin-top.c:863
#4 0x00000001000680ae in perf_top__mmap_read (top=0x3ffffff91d0) at builtin-top.c:876
#5 __cmd_top (top=0x3ffffff91d0) at builtin-top.c:1021
#6 cmd_top (argc=<optimized out>, argv=<optimized out>) at builtin-top.c:1352
#7 0x00000001000b643c in run_builtin (p=0x100277b08 <commands+336>, argc=<optimized out>, argv=0x3ffffffede0) at perf.c:297
#8 0x00000001000419e0 in handle_internal_command (argv=<optimized out>, argc=1) at perf.c:349
#9 run_argv (argcp=<synthetic pointer>, argv=<synthetic pointer>) at perf.c:393
#10 main (argc=<optimized out>, argv=0x3ffffffede0) at perf.c:537
Signed-off-by: Hendrik Brueckner <brueckner@xxxxxxxxxxxxxxxxxx>
---
tools/perf/util/namespaces.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/tools/perf/util/namespaces.c b/tools/perf/util/namespaces.c
index 5be0217..cf8bd12 100644
--- a/tools/perf/util/namespaces.c
+++ b/tools/perf/util/namespaces.c
@@ -139,6 +139,9 @@ struct nsinfo *nsinfo__copy(struct nsinfo *nsi)
{
struct nsinfo *nnsi;
+ if (nsi == NULL)
+ return NULL;
+
nnsi = calloc(1, sizeof(*nnsi));
if (nnsi != NULL) {
nnsi->pid = nsi->pid;
--
1.8.3.1
--
To unsubscribe from this list: send the line "unsubscribe linux-s390" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
