[PATCH 4.16 24/26] perf: Return proper values for user stack errors

From: Greg Kroah-Hartman
Date: Wed Apr 25 2018 - 06:36:33 EST

4.16-stable review patch. If anyone has any objections, please let me know.


From: Jiri Olsa <jolsa@xxxxxxxxxx>

commit 78b562fbfa2cf0a9fcb23c3154756b690f4905c1 upstream.

Return immediately when we find issue in the user stack checks. The
error value could get overwritten by following check for

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: syzkaller-bugs@xxxxxxxxxxxxxxxx
Cc: x86@xxxxxxxxxx
Fixes: 60e2364e60e8 ("perf: Add ability to sample machine state on interrupt")
Link: http://lkml.kernel.org/r/20180415092352.12403-1-jolsa@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

kernel/events/core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9730,9 +9730,9 @@ static int perf_copy_attr(struct perf_ev
* __u16 sample size limit.
if (attr->sample_stack_user >= USHRT_MAX)
- ret = -EINVAL;
+ return -EINVAL;
else if (!IS_ALIGNED(attr->sample_stack_user, sizeof(u64)))
- ret = -EINVAL;
+ return -EINVAL;

if (attr->sample_type & PERF_SAMPLE_REGS_INTR)